I enjoy the historical artifacts community if you aren’t already subbed to it. https://lemmy.ca/c/historyartifacts@lemmy.world

Theres also !Historymemes@lemmy.world which is cool. You could try and get the historians together so ask historians gets more business! I used to really like that sub

There is no equivalent to /r/askhistorians at this moment as we don’t have a massive collection of historians if that is what you are looking for

Nah, and It’s unlikely there will be any time soon.

Subject based instances have a habit of not being subject based without aggressive curation, which isn’t something most instance admins are willing or able to do.

Even literature.cafe veers off of literature to some degree, and literature is a very broad category.

There was a harry potter themed instance, but it’s closing down because running an instance with the current tools lemmy has is more difficult than the average small admin team can handle at a hobby level.

Give it a few years, and things might get to the point where it’s a realistic possibility though.