I would love to be able to still use other apps on my phone while still viewing, it would be awesome to have that floating little box like on YouTube or Facebook, how they have a movable box always on top in the corner of screen.
You can already do that. At least on Android 7 devices or above.
- Tap the app switcher button (square) in the bottom right corner of the screen.
- Find the app you want to place at the top of your screen, and tap and drag the app to the top of the screen.
- Find the app you want to place at the bottom of your screen, and tap to place it beneath the first app.