Feature request: smart wake alarm depending on sleep cycle

I'm a software developer and my understanding that it's likely won't ever come, at least not on watches that has extreme battery life, most likely smart wake up requires constant connection with the phone or doing a lot of computation on watches itself, I've had this feature on many watches before but neither was able to hold charge for that long. It may be operational system limit - i.e. either it's in power save mode or waste battery mode and nothing in between - which cannot be just fix but everything will need to be rewritten.
Possibly by enabling this feature you'll have a hit 30-70% in battery life. 

I suggest to look for an alternative solutions - maybe third party watches that will be used for that purpose only, a ring or anything like that.

It'll be helpful if someone post findings what's the best product to achieve that.

I'm a software developer and my understanding that it's likely won't ever come, at least not on watches that has extreme battery life, most likely smart wake up requires constant connection with the phone or doing a lot of computation on watches itself, I've had this feature on many watches before but neither was able to hold charge for that long. It may be operational system limit - i.e. either it's in power save mode or waste battery mode and nothing in between - which cannot be just fix but everything will need to be rewritten.
Possibly by enabling this feature you'll have a hit 30-70% in battery life. 

I suggest to look for an alternative solutions - maybe third party watches that will be used for that purpose only, a ring or anything like that.

It'll be helpful if someone post findings what's the best product to achieve that.

What's the problem with performing labor-intensive calculations within a range of +-2 hours from the alarm you've set?

I'm software engineer, too. It won't take that much energy to run smart wake alarm based on specified timerange, since almost every measure is already taken continuously. Garmin just doesn't take care of what its users are demanding. That's all (imo)

Why do you think this would consume so much more power? My Fenix7X already measure HRV, heart beats, etc. while sleeping and stays on for 10 days. Smart wake implies you define a timeframe of say 30min where you would like to be waken up in a light sleep; so if then it would consume more power during those 30min if it wants to be really accurate. But 30-70%? Please explain.

I had such function on 20$ fitness brasslet which I have charge once in a month. Any other ideas?