I think you are mixing things up.
Forgejo is one of the soon implementing, self-hostable software forges and one of the 3 listed implementations.
Codeberg is the (Github-alike) central forgejo server, where the team develops and which is also available for general open source coding needs. ForgeFed issues are tracked on Codeberg, so they already show their interest.
Codeberg is the (Github-alike) central forgejo server, where the team develops and which is also available for general open source coding needs. ForgeFed issues are tracked on Codeberg, so they already show their interest.