I have done pretty well with a combo of Nokia dumbphone for calls and texts, and a separate smartphone with no SIM as needed. I leave my smartphone at work or in the car when I want a break.

Only downside really is no WhatsApp but you can get a KaiOS phone that supports WhatsApp if it's essential.

Honestly the urge to constantly pull it out just passes after a couple of days. The boredom is intense but pretty soon you won't miss it and will enjoy other activities.

I also had good results with a very very cheap Android phone running Android Go. It was so slow that I just didn't want to use it for browsing. Downside is as a Dad I want to have a good camera within reach for special moments.