PS VITA is quite powerfull for its time it supports up to DirectX 10.1 and DirectX 11 I think, informations foud here and here. The console has a 4-core Arm Cortex-A9 CPU with 512MB of RAM and a 4-core PowerVR SGX543MP4+ GPU with 128MB of VRAM. RAM and VRAM are not shared and both are 64bit, if I'm not mistaken, today it is posible to safely run the CPU at 500 MHz and the GPU at 233 MHZ. Unity up to late 2018 version is also suported and more recently the comunity ported Godot game engine so games made with it can also run on the console.
Curently there is a lot of good available information regarding the development of games for the console, the best source is Vita SDK. The more recently games ported that I think are awesome to ever run on the console, and good examples of what the comunity has achieved are, Hollow Knight, Cuphead and Blasphemous.
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Keep the great work!