I'd like to decouple phone and "pocket computer", for both security and "digital hygiene" reasons.
So far, feature phones I could find are 4G at best. Though I definitely thought there'd be a market for connection sharing capable 5G feature phones. Am I alone?
Probably because the only things you can do on that phone are things for which there is a feature. That's what distinguishes it from a general purpose (smart) phone. Similar to the distinction between general purpose computer vs an embedded system.
I follow this market a little, and haven't seen one yet. The brands I'd check would be Nokia and Doro. There was a company making small power bank and feature phone combo but I can't remember the name.
It might be more fruitful to look at mobile broadband hotspots or whatever they're being called now. Could imagine a 5g one of those would be more likely?