I had the same question as the OP and after some research, I narrowed my choices...

therein on March 26, 2020 | parent | context | favorite | on: Ask HN: Best sleep trackers?

I had the same question as the OP and after some research, I narrowed my choices down to Oura and Dreem 2 and placed an order for Dreem 2 a few days ago. Happy to hear that people agree.