Sure, I did it 13 years ago and still use it daily. On a PC though, mostly. (But the actual player was mobile first, as it was my remote connection to the PC that is connected to the bass box. But works also standalone.)

I just never polished it to publish it, but it is quite easy and I guess ChatGPT can help with the basics as no arcane knowledge is required. (Except maybe the playing while screen is off.)

You also need a small node script, though or something different with system access to scan the media files. I think in browser tools make this now somewhat possible without(beware of security restrictions), but my approach is simply a node script scanning the music folder and generating a list that the media player consumes to find files for the player. I still didn't got around to make it automatic, but I don't add so much music (anymore).

I guess I will give it a try to see, how good it works a mobile player nowdays. I always wanted to upgrade it, so I can connect to spotify from my player as I hate the spotify mobile app.