I genuinely don't think it's possible for federated services to be "at least as convenient" as centralised alternatives, in general. At a certain point convenie

I genuinely don't think it's possible for federated services to be "at least as convenient" as centralised alternatives, in general. At a certain point convenience must come at a cost, and if you ruthlessly optimise for convenience like many of these centralised platforms do then you will end up trading away federation, privacy and openness. Email is probably the most convenient federated service out there and it is both (i) not that convenient (compared to things like WhatsApp etc) and (ii) not that decentralised (now being gatekept by a few big names like Google). That's not to say we should treat the fediverse as an ideological movement or that we shouldn't try make it as convenient as possible. But I think it will pretty much always be the case that when you choose an open, federated service over a centralised one you are giving up a bit of ease of use for other considerations.