The fact that these commits aren't in pull requests don't prevent you to apply them to your fork. You can simply add these fork as remotes to your repo, and cherry-pick/rebase/merge (choose the right one) commits from them. So it's just:
git remote add nice-fork https://github.com/author/repo
git fetch nice-fork
#then the remote branches and commits are imported in your repo.
If the commits you want are in pull requests, you can also get them.