I think Fiio and Hiby are the closest that exist today. They have dedicated hardware and physical buttons for the things listed in your comment. However, they do still ship with a custom Android OS and you need the touch screen to navigate your library and such. On the upside, this lets you choose your media library app. On the downside, it still isn't as good as the touch wheel on old iPods. I, too, am waiting for something like this to return. The Hiby is good enough until then for me.

Shanling uses a custom OS although it feels very primitive compared to iPods (e.g. the iPod Nano had VoiceOver for touch navigation). So I'm not really a fan of these dedicated single-function players; modern media player apps can be fast and convenient (more so than a clickwheel, honestly), and Android devices can still have dedicated control buttons. If only these devices weren't so bulky...

Shanling OS is trash. Absolute trash. Hiby OS is decent.

Fair argument, these devices (the Hiby R4, in particular, which is the one I have) are absolute tanks. Way too heavy and big to throw in your pocket for any reason, especially if you use a case. Still, it's nice to be able to (sort of) carry my own library around and never need internet to listen to it.

I've got the first boards on my desk for a media player based around the Sifli 58 chip. 1.8" amoled display and 16 buttons.

https://imgur.com/a/45GuaEA

https://forums.rockbox.org/index.php/topic,55419.0.html

Anyone want to help with porting Rockbox?

Hold on. You wear headphones while at the dentist? How are you supposed to carry on a conversation where they ask you question and you respond HOAYRA AH OT AH HA AH