The only comment I'd add here is that you should make sure you have a real domain, that you've paid actual money to, when setting this up. ActivityPub assumes the domain is immutable, and the free dynamic domain names you can get (or free TLDs like, say, .ml was) are a bad choice. Spend the $10 or whatever, because if something happens to your domain name, you cannot just update it in the database and fix federation: it completely breaks everything in a way that's not repairable.