Would it be possible for me to make comments to other instances etc?
Solved: I can’t, it would only work with a public domain.
You must log in or register to comment.
Additionally, HTTPS if very easy to set up nowadays and the certificates are free1.
1: Assuming you have a public domain name, but for ActivityPub that’s already a requirement due to the push nature of the protocol.
You can get Let’s Encrypt certificates for DuckDNS, so you don’t even need to own anything.