@Stan` Thx for the quick response. Tried it today again, now it works if i set the url to my fork. fetching and pulling from the 0ad-main repository is working. 

Much welcome.

[SOLUTION] My solution was to use ~/snap/0ad/657/.local/share/0ad/mods and I renamed all my variables from petra to felixbot. Here is my branch   ~/snap/0ad/657/.local/share/0ad/mods ├── FelixBot │   ├── FELIXBOT.zip │   ├── mod.json   Thank you !

Just to check you could make the lfs point to your fork instead.

I installed a mod in ~/snap/0ad/657/.local/share/0ad/mods/<name>. Then it was detected automatically when launching the game and I enabled it via the mod settings in the UI. I am running Ubuntu 24.04 and installed 0ad via snap.