Heh was about to post something similar, I'm not even on-call most of the time, I still check Slack when I wake up to see what happened to the person who was on call-if anything, since there's a 99.9% chance I'm getting roped in the second I get to my office. Best be prepared for it.

Not that I'm complaining about this, it just is what it is.

(Also because there's a sports radio show that isn't broadcast nationally from my hometown and I like to listen in as I'm waking up/getting ready for the day)

An intentionally limited device like an old-fashioned pager might work. I know it doesn't make logical sense to limit functionality: one might ask, "can't you just limit phone use to urgent notification instead of limiting yourself to a device that's physically limited to notifications?" Well, yes, but people don't work that way.