To be fair ActivityPub is a pretty shitty protocol in terms of scaling up with all the quadratic communication and caching growth it requires. Not that ATprotocol is better, just that there is room for improvement on ActivityPub before it could be used on a world-wide scale for the entire human population the way major social media sites are right now.

Ah, must have missed that one, though

Using the same profile as on mobile device is not yet supported – you need to create a separate profile to use desktop apps.

is a pretty major downside.

Seems like another one of those mobile only messengers, not really interested in those to be honest.