My Apple watch shows an message as "not available in your region" when try to enable blood oxygen level option. Watch connected to iPhone 11 and i tried all the options available in forums.
But issue is still there.
could you please support on this.
Is your watch and phone fully updated?.
Try force restarting phone and watch.
Check to see if it's available in your region;
watchOS - Feature Availability - Apple
Yes..... (Country: Sri Lanka)