You may be interested in a Garmin smartwatch then. They are primarily designed for exercise, so have very good optical-based wrist heart rate sensors, and are designed to minimise battery usage - I can easily get a week and more out of mine (a Garmin Fenix 5), even whilst making heavy use of its GPS and other functionality.

It really depends on if you sleep with your watch or not.

If you don’t then battery life is really irrelevant because you can rest your watch on a pad and have it charge just like if it were a normal watch.

I use an Amazfit BiP which does steps+ heart rate + sleep and lasts a month on battery. Would highly recommend to you.

Withings are about to introduce something with this capability.