> I don't want a smartphone OS, because then the battery life is inevitably going to be many times worse than the standalone mp3 player batteries of old. I don'

> I don't want a smartphone OS, because then the battery life is inevitably going to be many times worse than the standalone mp3 player batteries of old. I don't need an app store, or a battery-sucking high quality display screen for watching videos. I just want it to play my music. I think you're overcomplicating this. Modern mobile SoCs have evolved hand-in-hand with Android OS to be power efficient, perhaps equivalent or even better than the iPod Classic SoCs of the 2008 era. Using a modern 14nm or smaller process on a modern smartphone SoC isn't going to consume much power at all, even when running Android. The screen is primarily for the GUI, not video playback. If you have a giant music library, navigating with a full, responsive screen is far better than spinning the old iPod click wheel. The screen can turn off when you're not interacting with it. The products you're describing basically exist: https://www.fiio.com/m15 https://www.fiio.com/m15 Battery life is around 15 hours, it has very high quality components, it has modern charging ports, and you can drop a 2TB card in it for twice as much storage as you need. However, like all niche products it's not cheap. I think when most people see the price of a specialty, low-volume product like this they quickly become more than happy with just playing the music out of their phone.