If you are buying apple, go with the newest model! It's a nice machine. Pulse oximetry seems to work.The Apple Series 6 watch starts at $399
The Apple Watch SE starts at $279 and the only thing you don’t get is the blood oxygen app and the ECG app. Otherwise it’s the same as the Series 6
Certainly doesn’t have to cost $800 unless you HAVE to have the more expensive models.
Watch OS 7 just came out and is supported all the way back to Series 3, which came out in 2017. So you can expect at least 3 years worth of software updates to work with any new Apple Watch. Beyond that the watch will still function without the latest software update. And considering the sheer volume of used Apple Watches out there you can likely get any physical damage repaired well beyond 5+ years. Maybe not by Apple, but there are plenty of 3rd party repair centers and in my experience they are all cheaper than what Apple would charge anyway. And although, cheaper...it’s still costly. I can’t imagine it being any more costly than service on an expensive dumb watch though.
If you do not distrust CCP, Huawei has a small watch with similar functions as Iwatch, but it's $50. I wear one of these to go out now, but refuse to pair with a phone I use.
I still prefer for timekeeping an automatic watch (have a few).... but need the HR, EKG and maybe Sat in the watch sometimes.