If you're looking to detox, but don't want to regress all the way to a dumbphone, Unihertz has some great tiny Android phones: https://www.unihertz.com/
Everything works (Maps, Uber, etc) but the screen is so small you won't want to use it very much.
This is very appealing to me. I'm going to assume that the camera sucks, but I guess I could get back to carrying a point and shoot.
(Does a point and shoot camera exist that has the same smarts as a phone camera? Obviously a real camera with a better lens is the best, but that's bulkier. If I'm going to have a crap tiny lens, then I do think the phone's AI adds something.)
Just get a phone (iphone or android, your choice) and delete everything except camera, phone, sms. Include google maps and whatever else you want. You can even set parental restrictions and leave the code in a drawer to avoid needing to exercise self control.
Everything works (Maps, Uber, etc) but the screen is so small you won't want to use it very much.