Dear Tommy,
I have Raspberry Pi zero w running on
https://www.pimusicbox.com/ MusicBox. It is very stable, even after weeks not using it, it is always online. You can play local files and spotify. It takes some focus to get aquinted with MusicBox.
Originally I wanted to make a bluetooth audio transmitter with
https://www.balena.io/blog/turn-your-old-speakers-or-hi-fi-into-bluetooth-receivers-using-only-a-raspberry-pi/ Balena, but that was not a succes. The Pi Zero stutters while sending bluetooth audio.