AFAIK If you host GotoSocial it links out to the instances where content is hosted, rather than downloading it as a copy. I have a single-user instance on a tiny VPS and it uses hardly any resources. I think part of the reason for that is the above. You have to use a client application with it because there is no web interface, which I think is partly why it is so lightweight.

Might be worth looking at if you're concerned about accidentally hosting things you don't want.