TFA lists forks. rqlite comes to mind.
rqlite[1] author here. I wouldn't consider rqlite a fork in any sense, just so we're clear. That rqlite uses plain vanilla SQLite is one of its key advantages IMHO. Users have no concerns they're not running real SQLite source.
That said, there are some things that would be much easier to do with some changes to the SQLite source. But I think the message that rqlite sits on top of pure SQLite makes is still the right choice.