Well a country with a similar population mass would be Slovakia. They struggle to maintain an army of 15K and an airforce of 12 Mig 29s. Let alone a navy.
Slovakia is much poorer than Scotland. Finland is probably the nearest European country in population & wealth to Scotland. Denmark is next closest: about has about the same population but is richer than Finland, & Norway richer still, & less comparable than Slovakia.
Slovakia is, as said, much poorer, landlocked, & almost all its borders (save only a short stretch in the east) are with NATO allies or neutral & harmless Austria. It's currently negotiating to replace its old MiG-29 maintenance hogs with newer, cheaper to operate, Gripens.
Finland has a navy of small missile boats, mine warfare vessels (including several minelayers) & other small vessels. It operates in very different waters & circumstances from Scotland's. The Finnish air force has about 60 F-18 fighters, which it's kept up to date. Because of the constricted waters around Finland, it does not feel any need for specialist MPAs. The Finnish army is much more powerful than envisaged by the SNP. It has 100 Leopard 2A4 tanks, plus older Soviet tanks which it's about to replace with 100 Leopard 2A6; a lot more other AFVs than the SNP dreams of, & a massive artillery force.
Denmark is probably the closest in terms of circumstances. 24000 armed forces, plus 12000 reserves & 51000 in the volunteer Home Guard.
Navy: three 5500 ton 'frigates' (new) with destroyer armament, two multi-role ships on the same hull with light frigate armament, four 3500 ton ice-strengthened ocean patrol ships, two 2000 ton ice-strengthened OPVs plus one on order, six small patrol boats & a number of small miesweepers, survery vessels etc. More than the SNP dares dream of.
Air force: 30 operational F-16s (15 others are stored), scheduled to be replaced by about the same number of new fighters, with F-35A probably first choice. Four C-130J, four small VIP bizjets, 14 EH101, 7 Lynx (to be replaced by 9 SH-60) & 8 Fennec helicopters.
Army: 57 Leopard 2A5, & several hundred other AFVs fromm CV90 to armoured Humvees, & including a lot of M113s heavily upgraded by Flensburger.
Denmark affords that on 1.4% of GDP. That'd be about 1.7%-1.8% of Scotland's GDP.