It can be, but the certificate would be quickly revoked and signing ones aren't exactly cheap. Also app store does a little bit of app checking I'd say.
It uses RAM, though. And if I'm not mistaken, it could write to swap file. But I guess it's not an issue with screenshots unless one doesn't make million of those without deleting them.
I'd say Forgejo as it is the most simple of the three. If you want more complexity (like CI/CD), then one of the other two.
You can checkout Forgejo at codeberg.org.
Chinese to the rescue?