Game Input MultipleXer

Is there any advantage or any cool features a jailbroken PS4 can offer when it comes to GIMX support or just mouse and keyboard emulation?

I don't think so. Gimx is designed to work as a transparent genuine device for any console.

interesting question because OPL for example allows to use PS3 gamepads on PS2, even remotely. I love that feature
but that's not Gimx. You need to ask PS4 homewbrew developers what's possible on that front, if they are interested

DS4 requires authentication for a wired connection to the PS4 anyway. Even if you disable the authentication requirement in the console itself GIMX will still ask for it because it cannot know whether it is or not required.

PS4 have a Logitech.prx module, is this what contains wheel identification? I wonder if this could be edited to have enable native support of G25, G27 wheels?

It is possible, but the file is probably encrypted.

I decrypted the logitech wheel module from Assetto Corsa Competizione but I'm seeing nothing related to wheel IDs, so it probably needs the ps4_wheel_sdk to configure