Is it necessary to set device as preferred activity tracker in order to enable Sleep only Pulse OX?

We can enable Pulse OX Night only from Garmin connect mobile app without setting it explicitly as preferred activity tracker. However, if you try to enable the same from Garmin connect web app, it prompts us to enable Preferred activity tracker setting before enable the night only setting.

Scenario:

Fenix 6 as preferred activity tracker (with All-Day Pulse OX) for all day use.
Venu 2 (with Sleep-Only Pulse OX) for night use.

I got conflicting information from support.

Does anyone who has multiple Garmin watches tried this feature?

0 Dr Phil over 3 years ago

Only the PAT will record sleep therefore only that device can be used for tracking Pulse Ox when sleeping.

0 stroper over 3 years ago in reply to Dr Phil

I see. I was under assumption that both Venu 2 and Fenix 6 record sleep regardless of Pat setting. Thanks