That is exactly what Tapbots has done with Ivory - Taking Tweetbot and using that as the basis for a Mastodon client. I've been using it for the past few weeks and it's fantastic https://tapbots.com/ivory
Thanks!
I just prefer Ivory’s UI. For me, it’s a nicer app to use.
I do like Metatext but development is paused (repo is archived) - and notifications appear to have stopped working. I'll probably end up back on Toot! at some point.
(Tried building my own version from the repo but it breaks for some reason and I'm not an iOS dev who can figure out why.)