I like to run, but take the phone with me because it's my tracking device and music while running. I've been trying "do not disturb" mode, and it seems to be a positive. I don't get intermittent notifications that someone is trying to reach me - I don't want to be reached right now. The DND mode has probably been around for a while, I've just recently (last few months) gotten used to actually enabling it. What will be nicer is (eventually) have the device learn the times you don't want to be disturbed (beyond 'sleeping'). Or perhaps I'll just leave it on all the time....?

I’m getting a smartwatch with watch only runs, it has tracking, Bluetooth for headphones and can preload Spotify playlists.

It has WiFi but no cell phone. Really looking forward to just being out for runs, with no possibility of contact or checking notifications etc.

I do this with my WearOS smartwatch (gen 4 Fossil Sport). It works pretty well overall, although I had to find a third-party app (WMusic) to allow copying music to the watch and playing without an active connection to the phone.

I just got an Apple Watch, and am planning to experiment using it without the phone.

Maybe at that point a sports watch would be a good alternative? Something like Suunto, Polar, Garmin

Maybe it's an age thing. Maybe if we're coordinating an imminent get-together, but for the most part no one I know expects anything other than a telephone call to be immediately answered and even then understands reasons why it might not be.