In case you missed it, the Fediverse's livestreaming platform OwnCast has official apps:
iPhone, iPad, Apple TV
https://apps.apple.com/app/owncasts/id6451178968
📺 Roku
https://channelstore.roku.com/details/2179326b6b85869a1a3a18d48ca76de6/owncasts
You don't have to use these though, all of OwnCast's features are available through the web.
(OwnCast is like the Fediverse's alternative to Twitch, it's a livestreaming platform with a built-in chat service. More info at https://fedi.tips/owncast-live-streaming-and-chat-on-the-fediverse)