SDL_GameControllerDB VS devilutionX

Already planned to be in next update. As long as your controller is recognized by SDL2 and has controller mappings available (or you make your own), it will work.

Godot uses the SDL2 game controller database

Input fixes GameMaker's bugs. In addition to keyboard and mouse fixes, Input uses the engine-agnostic SDL2 remapping system for gamepads. Because SDL2 integrates community contributions made over many years, it's rare to find a device that Input doesn't cover.

The triggers are detected as buttons by default in some software (using d-input mode). Anything using the SDL2 community database shouldn't have this problem. I don't remember if RetroPie uses SDL2 or not. If not you might just need to edit a config file to rebind them to axes instead of buttons. I had to do this with Moonlight and linux Steam before the SDL database was updated.

# taken from line 1451 of https://github.com/gabomdq/SDL_GameControllerDB/blob/master/gamecontrollerdb.txt

I tried setting the SDL_GAMECONTROLLERCONFIG= from SDL game controller DB. Also tried remapping with jscal. Neither worked... and given that other games are recognizing it properly, I am puzzled.

It's in the project's README. Not sure what you had installed before, but the latest release of this project seems to be the first one with Vita support. There was another project that added Vita support, but I don't think you can upgrade from that vpk, since it uses a different data folder.

I don’t know of many games on the Vita that are like Diablo, but you can play Diablo itself on the Vita in a couple of ways: There’s a WIP Vita port of the original Diablo for PC here, or you could try the PSX2PSP version of the PSOne port of Diablo thru Adrenaline.