I don't want Facebook to have access to my account information, posts and comments.

I hate to break it to you, but the very nature of the fediverse (as a distributed network where posts and account information automatically get distributed to hundreds if not thousands of independent servers you may or may not be aware of, that do not necessarily have to honour your deletion requests) means that it would be absolutely trivial for either Facebook or any other random bad actor you could think of to have access to all of that, and there's not a damn thing you can do about it.

This is an example I've given a few times, but if Meta were really just wanting to suck down data for the evulz (why they would do this I have absolutely no idea because it's not like they could use that data for anything), they don't need to start an instance amid a blaze of publicity. They could just go on Mastodon.social, sign up for a no-name account, grab an API key and suck down the contents of the fediverse in real time and that's the end of it. The fediverse is not private and its very nature means that control over one's own data is not quite as secure as ActivityPub advocates would like to pretend.