A solution, funny enough, is to get a cheap android phone and don't connect it to a network. It's inexpensive, the storage is expandable, you can still get Spot

A solution, funny enough, is to get a cheap android phone and don't connect it to a network. It's inexpensive, the storage is expandable, you can still get Spotify et.al. installed and running on it, it provides USB-C and bluetooth, and some models even offer balanced headset outputs (Moondrop MIAD01). The downside is that you're carrying an extra device with very little real utility outside of playing music... which almost every phone can do. And since I already have a phone as part of my EDC, I sold the MIAD01, which did made me sad because I loved the idea but I never really found a usecase for it. Even the balanced headset outputs were done as well by a FIIO bluetooth headset adapter.