As a new peertube instance owner, I asked myself the same. I‘m not a huge programmer so I can’t tell you I‘ll do it but I think so too.
Peertube
A free software to take back control of your videos
Peertube is an open, federated alternative to Youtube without advertising or tracking. On this site, you can find a good Peertube instance, with good rules, good moderation and most importantly a friendly community.
It doesn't directly answer this need, but I think the reality is most viewers aren't on PeerTube at all, they're on Mastodon. And they're using whatever Mastodon client to watch PeerTube videos. Some clients support direct viewing and others will just show up as a link taking them into the browser.
A dedicated app would be a gamechanger for a very very small number of people, but until that number grows and while everyone is just using other platforms to watch videos, I can understand why nobody's gone to the effort.
Bill shock might be waiting for anyone silly enough to deep dive with peertube. And website hosts don't usually play nice when you want to start streaming media. I can see why a lot of people aren't jumping in with both feet.
You have to remember that YouTube has a gigantic corporation to back it. A lot of platforms tend to lean heavily on YouTube for content.
I think it's a case of waiting for another expansion in the Fediverse to make it all worthwhile. Otherwise, the app you develop could suddenly find itself disconnected from any instances willing to stream a large volume of content.
I might be wrong, but that's what I considered when thinking about contributing.
Framatube has an official PeerTube app on their roadmap for 2024.