To be honest, having good frontends for accessing the fediverse on mobile devices isn't really a waste of time, as it helps introducing the fediverse to more people. It's also more convenient for some users, I prefer to access Lemmy through Jerboa for example.
But there are always possibilities to increase compatibility and ease of use between the diverse ActivityPub platforms, there could be something like "templating interfaces" for different content formats, for example. I think it's mostly a matter of time and adoption, the more users something has, the more developers we can have, who'll be interested in making things more accessible and frictionless.