SourceForge never updated UX, some devs still use it but indeed github won. I think federated social interaction will win at some point. Git is distributed itself, but user accounts, follows, notifications, etc. would benefit of federation. Forgejo might make it sooner or later .
Not offline but self-hosting available , there’s LinguaCafe it’s like book reading web app with tons of niceties. I am yet to try it for myself.