I found worktrees unnecessarily painful in Git with little advantage over just having two copies of the repo.
Your far better off just having a clone of your primary repo, and have your primary repo as a local remote. Both can have a remote for GitHub and a separate remote for each other.
Genuinely curious, what did you find painful about it? A while back I found it annoying that I'd get errors when cleaning out my branches because they were checked out in a worktree I'd forgotten about, but git now highlights branches checked out in worktrees and has done so for a while.
It was the primary repo at my job at the time. Decades of history, migrated from SVN. Probably some ill-advised large binary blobs committed at one point or another.
Surely it's a tiny fraction of git repos, if not users. But if it's a problem you have, worktrees are very useful.
Your far better off just having a clone of your primary repo, and have your primary repo as a local remote. Both can have a remote for GitHub and a separate remote for each other.