You don't treat the symptoms; you treat the cause. dumbphones, minimalist phones, and crippled smartphones are as effective as a smoker throwing away a full pack, only to buy a new one when stressed or drunk. If you use doomscrolling as an escape, you will inevitably fall back to it when life hits. While a few may manage to change their habits with a restricted device if the stars align for long enough, it won't work for most. You need to first figure out why you do it.