I don’t think there’s one that supports all of them yet. Probably the one that can handle the most is fedilab, which can handle mastodon and friendica, as well as a bunch of others like pixelfed, peertube, and pleroma. There’s also raccoon, which has separate apps for lemmy and friendica.
Have they been using AI art? All of their art that I’ve noticed has been from David Revoy.
And it’s a fairly small open source project that only started working on the phone app last year. It’s not that surprising they haven’t gotten apps for every platform yet.