Use my Benq projector remote

Hello!

Beginner here, so apologize if my question is stupid, but after doing researches, I'm just very confused about where to look.

I want to use my Benq projector remote for Libreelec, how can I achieve this?

My setup is:

- Librelec 10.0.1 on RPi4.arm

- Not a vanilla RPi: I added a Hifiberry Amp2

- Projector BenQ TH585

- RPi4 and projector are connected by HDMI

What I understood so far:

- I could use "CEC" to use the Benq remote control on Kodi. Is it suppose to work out of the box? I had a look at the settings and got scared to break things. (And the CEC adapter is already enabled)

- I also saw somewhere that the HifiBerry Amp2 were using "GPIO" pins and that it could be an issue with remotes. I don't understand what it means and can't find where I read this (maybe here?), so maybe I'm saying non-sense, but I just wanted to gather here everything I found so far.

- I could use Flirc2. Is it relevant for my case?

Sorry if that's all confused, I'm just a bit lost, not being very tech-savy. Any help/clue/hint will be much appreciated

Okay thank you very much!

In that case it definitely does not work out of the box for me

So if it does not seem to work, the issue can be either the projector, the cable or the raspberry? Is there some utility to troubleshoot this? Otherwise I think I'll give up, I can even find a single occurrence of "CEC" in the projector manual or data sheet, and it looks like the problem could be anywhere in the chain.

Also, could the fact that I'm using a HDMI cable + HDMI to micro-HDMI adapter be an issue?