Just a quick update on my game though it's probably distracting at best.
This time I loaded an old save two years back and focused on navy construction and oil production, building as many synthetic refineries as I could fit in my land. With all the technology this amounted to 1.8k extra production, not enough to be secure but I was able to make up the difference with judicious use and sacrificing production to buy oil on the world market. It wasn't challenging in the fun way as I had to micro my planes constantly and hold them when enemy bombings stopped. However, I never got below 50% in reserves so that was reassuring.
I also moved faster when I declared war, promptly landing troops on Trottingham as soon as the coast was clear. This was a handy base from which to launch bombers to obliterate the enemy navy. Naval bombing is as OP as it is in real life as Prywhen losts countless cruisers, battlecruisers, carriers, and battleships to my coastal bomber presence. Combining this strategy with submarine warfare made being a Prywhen sailor the most dangerous profession in the world.
In reality I think the Kingdom of Prywhen is a paper tiger despite the excellent buffs it gets with national spirits. You can see how much land it has in the first picture. However, only the Changelings who had been previously castrated by Equestria looked to be in any serious danger, though I'm sure Olenia would have fallen with enough time. I was preparing to launch a D-Day into Equestria but both the Changelings and the deer beat me to it, but my reinforcements helped secure the eastern coast. Although Prywhen had nearly a thousand divisions the few I encountered were 20-width and melted before me, though that may be because I was using space marine templates and fully upgraded griffon knights. The whole enemy army looked to be starved by the time and I didn't face any major offensive, but maybe that had to do with Equestrian resistance. Fascist Stalliongrad joined the war after I already took the northeast and the first thing they did was nuke Canterlot. Anyway, it took only a year after the outbreak of war to completely secure Equestria, with the Changelings somehow occupying more land than Chrysalis ever did. I'm confident Griffonia will be more challenging though I wish I could use "ally" airfields.
I should have screencapped war participation, but I have 35%. I barely have any ground casualties with about two million for our side total, but Prywhen has taken over twelve million after losing the entire army in Equestria.