Maybe check how long it is already going, so it can give you some confidence. Forgejo is a fork of gitea, which is a fork of gogs.
Also, codeberg, a nonprofit from Germany, is supporting development.
https://docs.codeberg.org/getting-started/what-is-codeberg/
The codebase history of Forgejo and its predecessors predates Codeberg. However, since 2022, Codeberg is backing the development of Forgejo as an umbrella organization.
There are some really nice designs here. I really hope that KDE finally gets to pay attention to this. I love simplification of it.
One thing I don’t like here is the login screen. There is too much stuff on it. I think gnome’s login screen, as it is now, is fantastic.
And one more thing, proposal for mindset change: not everything has to be a widget. Some things (like shell) could have layouts: layout as current plasma/windows, layout as gnome, layout as Mac, layout as Win8… If things get well thought out, you can integrate this and switch layouts and not di*k around with widgets. Less moving parts, less problems.