A server hosting a copy of the repo, git send-email, a mailing list and a bugzilla instance is all that an open source project really needs.
The advantage of github/gitlab et al. is that it merges all of the above functionality to one place, however it’s not absolutely essential. Git itself is extremely versatile and can be as useful as you are want it to be if you put in the time to learn it.
A server hosting a copy of the repo, git send-email, a mailing list and a bugzilla instance is all that an open source project really needs.
The advantage of github/gitlab et al. is that it merges all of the above functionality to one place, however it’s not absolutely essential. Git itself is extremely versatile and can be as useful as you are want it to be if you put in the time to learn it.