I'm happy that this hardware exists but an easier solution is to quit social media, viciously curate your notifications and apps, and install an ad blocker. My phone only alerts me if somebody calls me, asks me a question specifically in a group chat, or DMs me. I never see any ads or any FOMO nags. Life is pretty good.
This. I still struggle a bit with compulsively checking Slack or email during the workday, and sometimes I take extended breaks from HN just to avoid the time suck (among other things) but this + quitting social media entirely 2 years ago means I got my attention span back.