Object type support by software?

More or less what it says on the tin - I’ve got an idea I’m toying around with for what is essentially an archive of writing/images/audio/video (depending on what the user wants to post), and I’d like to use AP as a mechanism to enable update notifications (as well as commenting/likes). However, I can’t find info on what object types different software supports, and what they do with objects of unknown type.

For instance - I use microblog.pub which allows creating both Notes and Articles. I know Mastodon supports Notes, and renders Articles as links. I don’t know what any of the Mastodon forks do, or Misskey or Pleroma, and I do know that friends have had issues not receiving objects from servers of a different type than their own (notably Bookwyrm and Pixelfed, iirc).

I know global compatibility isn’t going to happen, but I’d like to at least support major platforms that offer some sort of personal feed/timeline view for users.

This is a topic that also concerns me!
But at the moment I have other priorities.
There should be a supports endpoint to which you send a list of http://www.w3.org/1999/02/22-rdf-syntax-ns#type and which then returns true/false per item.

The best form of documentation you can find for this is probably given by FEDERATION.md, see Guide for new ActivityPub implementers