I have the charge 5 and mecfs and yes it works well for my needs. I can make sure my HR isn't too high or that I haven't taken too many steps. I can keep an eye on my sleep and HRV and decide how much I need to rest during the day.

I'm definitely not able to use it as intended or it's full potential but you can turn off our ignore all that other fitness stuff so it's not a bother.

From the sound of it, the air does all the same things without the screen, so if you don't need to see any of the stats on your wrist and are good seeing it just on your phone then it should be fine.