I already did that as did countless others over the past few months. Would love just one example of Apple changing things...over a decade later of using Apple products exclusively (MacBook, iPhone, iPad and all the accessories) and I haven't seen that to be the case, myself. Maybe you know better. Having said that, my solution is to go back to my original Apple Watch that has the interface I need and return the new one I just bought and will buy a continuous O2 monitor as that is the only reason I wanted the new watch, and that will save me about $300! (Good continuous O2 monitors run in the $150 range.)
And anyway, here's a news flash: the O2 monitor on the Apple watches requires one to be perfectly motionless for 15 seconds - difficult to do when one is heaving/panting with low O2 levels. So it's back to my SE 1st gen, I'm sure I'll be happy with it for quite a while longer: I was perfectly happy with my original (used) Series 1 for years. Fortunately I'm not one to always need the latest, greatest, most up-to-datedness tech! ;-)
Hope everyone else can find a solution that works for them!