My pocket device needs these features: (a touch short of absolute requirements, but who’s counting)
a nice camera; cellular connection for data, sms, and voice calls; receive notifications from various apps (email, school, daycare, whatsapp), actually open the apps that don’t put all the relevant information in the notification; and play spotify and libro.fm with a speaker and bluetooth headphones.
While reducing excess usage in ways that are not too complex to configure, and also not too easy to disable.
Maybe I could get close with a wifi camera + a cellular watch?