I created lockmeout.online for that specific purpose - change your phones unlock code to a randomly generated one and time-lock it away for a period of time you want to be free of distractions. Carrying a locked phone is still pretty usefull: Emergency calls, take photos using camera, taking/making regular calls using Siri, Music, Background GPX tracker etc.

Maybe a map for navigation.

And banking apps.

Music player.

I have multiple iPods and it’s a shame I can’t use them with subscription services. It’s too expensive to buy all the music I like because it’s just the perfect use case. You highlight 2 important use case though that are almost impossible to have without a smartphone (but an alternative can be done on the desktop computer and the map with a paper map). They are just the collateral because it’s not those that cause addiction …

Get an Android phone and uninstall the Play Store and built-in web browser via adb. Gets you Maps, Spotify, banking etc. and nothing more.

I have a kitchen phone and a desk phone (both VOIP), a Linux workstation, a DSLR camera, a radio, and read real books and play CDs. Also an RCA Orthophonic High Fidelity phonograph for 78, 45, and 33⅓. After the last Star Trek went off the air, and Jeopardy! went woke, there was nothing to watch on TV and it got left behind somewhere.

Computers are nothing but free software. Had a mobile phone (a flip-phone with real buttons) for years but never used it, and just let it lapse, as being unnecessary. Never understood why so many folks bought into being abused by their handheld pocket computers, and paying for the "privilege." Anyone who gives MS/Apple/Google/Amazon (the evil MAGA) money is being an enabler for the abuse of others.