I am at the point where everything seems to work except for confirming the follow/unfollow request. It is something about the signature.
These past few hours of development remind me of what @coachtony says in the last episode of #dotsocial by @mike, there is not a nice way to test your #activitypub implementations.
Different #mastodon versions, return different errors, there is no test suite, and basically I am testing in production and/or setting up my own #mastodon server.