Game Input MultipleXer

Check USB cables, may be broken or bad quality, check solders, check pins to pins connections, do not use USB HUB.

I don´t know if it could work with steering wheels but you didn´t follow the steps correctly, maybe I wasn't clear enough, both USBs from GIMX should be on PC, nothing will connect directly on PS5.
You should test first if G29 works via Remote Play or Chiaki first and then try this workaround.

You can use external software to do the macro, on gimx-launcher change input to windows events, some macro programs should work.

I think it can be solved by spliting MAXIS 1 2 and MAXIS 0 2 on two different conditions. KEYDOWN h for MAXIS 1 KEYDOWN j for MAXIS 0 Something like: MACRO KEYDOWN h MAXIS 1 2 KEYDOWN h MACRO MBUTTONDOWN BUTTON_LEFT KEYDOWN h MACRO MBUTTONUP BUTTON_LEFT KEYDOWN h KEYUP h MACRO KEYDOWN h MAXIS 1 2 DE...

So far the team is working to make the GIMX adapter work on PS5, while it is not possible there is an (ugly) way to use it and it is through Remote Play. I use Linux which is my daily operating system but it should work on Windows. I didn't test with steering wheels, with mouse/keyboard/joystick is ...

If I understand your situation well, your shifter does not work with G27 but somehow is working on PC, if that's the case seems you can use GIMX adapter to go over it.

Is Raspberry pi Zero armel ? I don´t have a Raspberry Pi Zero to test it or compile for it.

Is custom firmware on switch required ?

Long time since i don´t compile on Raspberry because there is a already pre-build binary at: Github: matlo /GIMX / releases gimx_8.0-1_armhf.deb

Your instructions should do the job, but you can follow a more detailed guide from here:
Development_on_Linux

Hi Henrique;
Welcome!

I'm from Brazil too, any doubts feel free to ask in Portuguese (in the Brazilian corner subforum).