If you have ever searched for open source keyboards, you might have come across OpenBoard. But that project hasn’t seen development in more than an year. Thankfully, there is a fork of it that is being worked upon quite actively. It already supports autocorrect, glide typing, user-defined dictionaries, multilingual typing and now material you themeing as well.
Why isn’t the fork on F-Droid instead of the “original”?
They have it planned if you go through the ReadMe in the repo, some work needs to be done before that.