Dr Raoul McLaughlin has some interesting older uploads about ancient Roman contact with China.

Myron Cook (a retired geologist) can be interesting, but has a younger target audiance

Nick Zentner is a geology 101 teacher at the University of Washington and does a lot of interesting content

Parallax Nick does astronomy history content that is really good.

Geology Hub is 5× larger than the limit but is a relatively new, fast rising must watch for what is really happening in geology news like reporting about all active volcanoes and events in short 5 minute vids

Looks like geology is under appreciated IMO/watch list.

Another good larger one is Stephen Milo.