Mine has 128GB of onboard storage... but Apple still bans apps from downloading video, which annoys me.
The streaming apps virtually all support downloading for offline viewing on iPhone, but the Apple TV just becomes a paperweight when the internet goes out, because I'm not allowed to use the 128GB of storage for anything.
If they're not going to let you use the onboard storage, then it seems unlikely for them to let you use USB storage. So, first, I would like them to change their app policies regarding internal storage, which is one of the purely software improvements I would like to see.
I use a dedicated NAS as a Plex server + Plex app on Apple TV itself for local streaming, which generally works fine. Infuse app can also index and stream from local sources.
But there are some cases like e.g. watching high-res high-FPS fractal zoom videos (e.g. https://www.youtube.com/watch?v=8cgp2WNNKmQ) where even brief random skipped frames from other things trying to use WiFi at the same time can be really noticeable and annoying.
The streaming apps virtually all support downloading for offline viewing on iPhone, but the Apple TV just becomes a paperweight when the internet goes out, because I'm not allowed to use the 128GB of storage for anything.
If they're not going to let you use the onboard storage, then it seems unlikely for them to let you use USB storage. So, first, I would like them to change their app policies regarding internal storage, which is one of the purely software improvements I would like to see.