@witten I have switched maybe a year ago or something like that. Didn't loose anything because I was running a compatible version at that time:
https://forgejo.org/docs/latest/admin/upgrade/from-gitea/

If you are running a recent version it's probably a bit more complicated.

@yaroto98 @Carol2852 Same here, switched from gitea to forgejo. I still was using the act runner for some time, later I replaced it with the forgejo-runner.

Works pretty smooth!