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?
If I need anything besides SMS/MMS and voice calls I turn on a hotspot and take out my laptop. I'm "offline" by default but still reachable in emergencies.
I do cheat on the camera portion by using my partner's smartphone for pictures where I care about the quality.
You lose conveniences but the tradeoff was very worth it in my case. I have no plans of going back to a smartphone.
I do find that https://freedom.to/ is one of the few things that has worked for me. It’s more difficult to bypass than ScreenTime, and syncing blocklists with the laptop during the day is great for overcoming procrastination. It works through a VPN profile (though not an actual VPN), so it also blocks apps.
I‘ve used it with schedules that go from 05:00 to 19:00 and it’s just such an eye opener when even a week after implementation I still open safari and reflexively type the urls for Twitter, hacker news, and Reddit even though they’ve only produced blank pages for days. Restricting it to the evening and going a couple of hours longer than the workday means I can still enjoy some mindless surfing but if I get busy doing something else I’m less likely to get sucked in. I also really like some of the suggestions here to restrict time wasters from the phone completely and only do social media stuff on the desktop. The extra effort for me to go to the office would mean that I’m more likely to use the time doing something else.