I read these a long time ago... but I still keep them because they look neat on my shelf :D There will be a second part in a few(I hope lol) days since I couldn't record everything at once... In case anyone cares xD
To listen while using other apps, switch the player to Picture-in-Picture (PiP) during playback — it keeps playing in a small floating window (the screen stays on).
To listen with the screen fully off, in-browser playback stops by YouTube's design. Open the video in the YouTube app to keep listening where background playback is supported (e.g. with YouTube Premium).
Open in YouTube app