As a recreational diver I meet many people diving within recreational limits that don't use diving computers at all (they usually rely on their DM or guide dive computer which is good enough for < 30m dives people do recreationally).

For that reason the Apple Watch Ultra seems just fine - it doesn't seem to have any less features than my dedicated Suunto D5 (outside missing integration with air tank) and it seems to be a good competitor to Garmin's Descent MK2 series of diving computers (which are pretty amazing but cost 1200$+ with tank pods).