> I looked pretty hard - I specifically don’t want an android OS called an mp3 player. I want a dedicated media player that has physical button controls (not touch screen), is very snappy, has a good UI, and has a purpose-built OS
There are a lot of DAPs in this style. They're just not popular because the Android-based units are perfectly fine and don't feel like Android phones with an MP3 player app installed. Most buyers don't have arbitrary OS requirements, they just want a device that works well.
I'd start by looking at the Rockbox compatible devices list: https://www.rockbox.org/
They likely want to use the device without looking at it, thus the requirement is physical buttons not a specific OS.
It’s the same issue with touch screens in cars. Anything that’s a touchscreen simply fails a core MP3 player requirement for many people.
For me it's not arbitrary. An android device is a general purpose handheld touchscreen computer that happens to be used for music. That means a bunch of things to me:
1. "Touchscreen first" UX
2. Heavier than it needs to be
3. Worse battery life compared to a non-Android device
Using a touchscreen in the rain is impossible. Running out of battery sucks. Going for a run with a 240g brick is no fun, it'll pull your pants down to your knees and trip you.
Compare the specs:
These are the things matter to me, in addition to the UX, sound quality, Bluetooth support, expandable / removable storage and sane file-based playlists.