The endless amount of Chinese Android-based single purpose mp3 player devices that are obviously iPod Nano/Classic clones basically cost ~$30 and have 50hr+ of battery life. You don't have to think about what player app to use, they ship with the only one that runs. The rest of the Androidness is stripped out.

Then yes, there's obviously the other end of the extreme where the mp3 player is very obviously a phone without a radio with a price tag to match. And everything in-between.

I'd say there's actually too many choices cause the silicon and battery cost required to simply play music has gotten so cheap that it doesn't make sense to optimize the OS further than Android. I'm sure the economics of scale means the actual hardware wouldn't be cheaper by any noticeable amount either.

> Only speaking for myself, but the problem with Android is that it and the hardware needed to make it run acceptably are absurd overkill for the use case, which drives up cost, cuts down on battery life, and adds a layer of unnecessary complexity (suddenly you need to think about what player app to use, for example).

The battery life is fine on modern DAPs. Excellent, even.

I understand why an engineer would want a completely application specific, built-from-scratch OS that does one thing perfectly, but that's a pipe dream for a niche market.

A powerful and efficient SoC that runs Android is ultra-cheap these days. Less than $1. Hiring an engineering team to write and maintain a custom OS for a niche product would incur so much R&D cost that it would wipe out any money you'd save by using a smaller microcontroller and drive the final cost up.

Just think: How much salary would you have to pay a team of engineers to write the custom OS and maintain it? If you could optimistically sell 500,000 of these devices (good luck) then how much would you have to save in order to pay for the R&D?