I have a (dumb) question that I’m not sure you can answer. So my home instance is lemmy.one, and say there’s a porn instance. Porn isn’t allowed on my instance, but I can interact with and post to other instances. So I post a picture to a community on the porn instance. Is that content hosted on my home instance (against the rules) or on the porn instance where it’s allowed?

Same. Never cared about Twitter, but I like new internet stuff, so I got on Mastodon. Never used it and forgot about it for years. Came back to it with all the Elon stuff and realized the instance was dead, so I created a new account on another instance to never use. The point is, like you said, Lemmy is something I will actually use if the community continues to grow and sticks around.