Another implementation (javascript, not python), you can take a look at is the one used by https://github.com/dariusk/rss-to-activitypub (which reminds me of the proxy side of this discussion, RSS being the API calls, and activitypub on the other side) : Express ActivityPub Server https://github.com/dariusk/express-activitypub
The UX is really simple : enter a RSS URL, choose an activitypub username, which can then be followed from the fediverse (read-only, no interaction).