Hi! This is a really good question. To make it more accessible we won't make it a requirement for everyone to post their repo and make it open source itself as newbies might not have experience with using version control or things like Git and Codeberg.
We're mainly trying to promote open-source in the first place for all things games development, it's slightly more laid back though as newer game devs might not have experience with open-source game engines yet, so if they at least use SOMETHING that's open-source (like trying Krita or Blender for their artwork or asset models) at least we're slowly introducing more people to experiment with things over time ʕ·ᴥ·ʔ
Massive bonus if people include their source code / repos and make their game itself open source though, as it's fun to see how people developed a game and it can be useful teaching people how to code certain mechanics and exploring other's source code too. I'll add a rule saying it's not a requirement but it is highly encouraged!