It works but I don’t think Forgejo plans to support it in the future. Gitea and Forgejo started to diverge and the documentation regarding docker is somewhat in a deprecated state.
Edit: I also think the OP’s question is different from this. So this might not be a solution.
I have a different experience. There was one thread which linked to a github issue. The issue said some blobs don’t have source code. Ironically when I went on to check, the blobs mentioned in the issue had source code, but there were other blobs which seemed to miss the source or build instructions.
I would love to have an independent audit to put this issue at rest. All that happens is more and more noise and no resolution. I am not a programmer so can’t really help here.