Just run podman or docker login your.forgejo.instance.address then push to it as normal. An existing repo must exist. You can check the images under site administration -> packages.

Speaking of authentication it also works as an openid provider meaning you can authenticate every other web software that supports it to Forgejo... which in turn can look for users in other sources.

It also has wikis.

Its an underrated piece of software that uses a ridiculous small amount of computer resources.