I Play around with lutris. What is the minimal need lutris have to register an application?
I copied a working wine Prefix into the Game directory.
and created a yml in ~/.local/share/lutris/games/
But the app does not appear in
Try ~/.config/lutris/games 
In config does not exist a lutris directory
(fresh installed Ubuntu 25.04 and lutris from deb repository)
Maybe it’s because my lutris data has existed for a very long time, but I have both ~/.config/lutris and ~/.local/share/lutris and they both have different parts of lutris data in them. My Runners and Runtimes and covers/thumbs etc. are in ~/.local/share/lutris and my configs are in ~/.config/lutris
However on further consideration, I suspect that what you are missing is entries in pga.db (an sqlite database) in addition to the .yaml files. Mine is ~/.local/share/lutris/pga.db and I can see text strings in it that correspond to library entries. That doesn’t bode well for what you are trying to do, unless you can do manual queries to populate it.
yes it seems this db is the missing point.
that’s bad.