I don't own an Amazon smart device and I don't think I ever will so I cannot comment on whether there is actually a need for a feature like Sidewalk.
Find My is also opt-out instead of opt-in
Find My is also opt-out instead of opt-in
The sheer fact of asking the user to opt-in automatically decreases opt-in rate a lot (like a LOT), even if that tech is super good. It is way easier to dismiss a dialog than to think what it even does.