This is an example of an elite Mercenary. An ex army conscript with real combat experience, and then enlisting to U.S. Army as a Foreign Mercenary.
Worked with the Green Berrets, and portayed as some kind of hero who saved some American Soldiers with a self sacrifice, and never returned home. And whose role in the U.S. Army was actually an instruction or a teacher of specialized warfare.
You can of course screen your recruits, and take only those who you deem viable in the Service. If you want, you can also limit your recruits to those with real combat experience, or army backround. But a lot of solid people come from civilians with no combat experience, or army backround. You can also educate and instruct them. Drill them into viable units. You do not need to just throw them in the field with nothing to prepare. And you can mix in more greener recruits with those with actual experience as squad leaders.
However you want to arrange. But more often than not, its well worth the money if your objective is to win a war and you are not doing that well.
The France have also this Program called "Foreign Legion". The Roman Army had a conscription system too, and at least half of their troops were Auxilaries who came from foreign backrounds and fight for money. I would not call Roman Legions, or those Mercenaries especially weak. They were actually one of the finest. They had dire training regimes, and each of them were specialized in certain craft. There were also specialities the Romans did not have, and especially their cavalry were usually foreign mercenaries, that come from north africa.
The actual legions were usually Roman citizens, and their system was very successful and one of the most efficients in that time. Without Mercenaries, they would not have fared too well.
The life of a Roman Legion might not even include actual fighting. Some of them were stationed on vassalized areas, and they were so infamous, that even one Legion could hold a large territory, by just being there. The presense of even one Legion suppressed all the thoughts of mutiny in the local populace, even there would be tens of thousands time more people than in the Legion and the area the Legion was stationed in would be large, such as the area of modern France. The difference of there not being a Legion, and there being even one Legion was huge. It was a symbol of Roman rule, a presence of oppression, and meant that they could bring more. And the Legions itself would never have been successful without the use of Mercenaries. The Legionaries itself were one of the finest on their craft. But so were the Mercenaries. Slingers, Archers, Skirmishers, Scouts, Light Cavalry, Heavy Cavalry and so. The actual Legionaries being the Heavy Infantry, which forms the core of the Legion, and keeps the Legion in check. They advance the middle in the Shield Formation, while the Auxilaries harass and control, and keep the flanks.
Some Mercenaries have their pride of their own. And even to this day, there are some Martial Mercenary Traditions such as the Gurkha Tradition in Nepal. Russians have actually used Gurkha Fighters they have bought from Nepal. They have Mercenary Schools, who train young boys to be elite soldiers or law enforcers and especially Signapore hires them as Polices, India hires them in the army, and the UK have traditionally kept a Gurkha Battallion. But i suppose, the India made a coup with Russia, so that they did not hire, and dissolved some Gurkhas, so that they have no one to hire them. Allowing Russias to hire a large Group of Gurkhas and then some untrained Nepalese Civilians to fight under Russian Army in Ukraine. Getting a few Gurkha Brigades, or even a Battallion is a great boon to your Army. They are disciplined soldiers who come from a martial tradition.
For Ukraine, it would be way more advantageous to be able to hire the Gurkhas to fight with them against Russia. Rather than fight against Gurkhas that have been recruited by the Russians.
Gurkhas are Mercenaries and the whole point of their tradition is to become Mercenaries, so that foreigners hire them as Soldiers or Specialized Police units that have been trained to combat situations. For Riot Control, Hostage Situations and so. This is the life they choose, and in Nepal some of the people might have little other options.
I would not exactly say, for example. That hiring Gurkhas lead to bad things, and result only as a Mutiny. They too have a reputation to upheld. And it wont exactly help to hire troops that have been graduated from their fighting schools if they dont behave and offer value for your money.
Africa is full of all kind of militias and insurgents who have real combat experience, but might be less disciplined than for example, Gurkhas.
Latin and Middle America is full of all kind of criminal organizations and cartels, who have hardened people with real combat experience.
Middle East is full of all kind of people with real combat experience, or at least experience in the conflict zone. The latest achievement is in Syria, where an insurgent civilian Group succeeded in a coup against their actual standing army (al-Sharaa). In Mali, they are now attacking their military junta, which is backed by the Russian Mercenaries. And upon last information, the Russian Mercenaries were forced to abandon their positions.
Afghanistan is full of insurgents and hardened folk, who are specialized in guerilla warfare and using mountanous terrain. And its also one of the poorest regions on earth, with incomes similar to few dollars in month. 100 000 dollars might well mean World to them, if not for their entire village. One of them leaves as a mercenary, then everyone can prosper.
Any of them might well offer even a trained professional career soldier a run for their money. And might know a trick or two they never even heard of.
And of course Russia, is full of Mercenary Companies like Wagner Group and even the United States had one, operating in Africa, which i think is now dissolved. Bakhmut i suppose, was mostly captured by Wagner Group Mercenaries. They had a high amount of losses and were using mostly Convicts that were recruited from Prisons on prospect of getting out of Prison after the Service. But got the job done regardless and forced the Ukrainians to pull back. They formed these so called Storm-Z units, who were then pushed against Ukrainian positions endlessly until the Ukrainians ran out of steam and the mercenaries, did not. And after this, the remaining Mercenaries were supposedly released, and went back to Russian civil society. The amount of convicts they used were stated among the lines of 200 000 and the amount of casualties they had was reportedly around 50 000 in the Bakhmut sector only. So some of them actually survived, and become free citizens in stead of a life in Prison or so. And some of them, of course conducted new assault on Russian civilian populace like rape, murder and such and are back in Prison again. But because they are now War Heroes, they supposedly treat them better than normal convicts and are feeling somehow special for that.
How i understand, also Ukrainians have adopted a use of convicts to some extend. And how i have been told, they use Mercenaries they hire from Latin American drug cartels, who then come in the disguise of a volunteer, but are actually paid to come fighting in Ukraine. I do not know is this true or not, but there are this kind of rumors and if you think about it, it makes sense. They need more soldiers, same as Russia. And while your casualties pile up, you need new soldiers endlessly. If you cannot bring them, your army just might crumble for having manpower shortages. The casualties in the Ukrainian and Russian troops are somewhere along the millions. If not now, before long, it will be. And you need to constantly bring some more. Especially, if you are the one advancing.