I bought a used japanese PSVita for my 18th and it arrives tomorrow, what games should I get?
wipEout 2048 and Minecraft Vita Edition are already on the list, and I will be installing homebrew.

I'd recommend getting Tony Hawk's Project Mod if you're a fan of the THPS series

Nidhogg, dosbox with windows and run worlds on ur vita.

Might actually be possible to just install Windows 95 on the thing, though knowing how my beefy gaming PC struggled to emulate a Pentium 2 on 86box I doubt the vita would have a good time.
https://vitadb.rinnegatamante.it/#/info/798

I wanna see how well this works just for shits and giggles. I've messed around with adjusting clock speeds and the Vita really is mostly limited by its CPU cycles and not so much its resources overall. wipeout 2048 saw a 10 FPS increase just from maxing out the GPU clock to it's rated capacity which was under clocked by the game devs for battery life probably. There are ways to overclock it even higher at your own risk. Doing this carefully I could probably get a 686 or Pentium era emulator running on the thing at usable speeds but I'd have to be extremely conservative. This should definitely be enough for MS-DOS 6.22, Windows 3.1, and Worlds Chat Gold. WorldsPlayer on the other hand I have my doubts about.

DOSBox isn't exactly an option because 1. I don't know if Retroarch for Vita has a dosbox core I can use and 2. The PSVita is basically a glorified ARM smartphone and it can't natively run x86 code, so dosbox wouldn't be any better than a hungry cycle-accurate emulator like 86box.

P.S. I tried Nidhogg as you suggested and it's a pain to control but very fun. Was worth taking on my Scotland trip last year :)