Added type hints

[radarhere]

Since there are parts of #8032 that I still have questions about, this is a PR with the parts that have my approval, as a partial merge if you will.

[hugovk]

Maybe add Co-authored-by to the commit?

https://docs.github.com/en/pull-requests/committing-changes-to-your-project/creating-and-editing-commits/creating-a-commit-with-multiple-authors