I guess I'm the last one to find out about this :|
I ditched my Intel Mini today and upgraded to an M1 mini, remembering that during the original presentation, Apple touted the ability to run iOS apps natively...too bad they didn't mention that many of the most useful apps and games would be locked out. Oh well.
Even the apps that are NOT locked out, like HBO Max, suck pretty hard on a 4K monitor.
There's no way to make the video actually run full screen - when you full screen the app, it full screens _everything_ and it's stuck in the iPad aspect ratio, meaning there's letterboxed black bars on the sides.
Better just to use the browser version I guess.