Unlock Apple Watch app with iOS app subscription?

My team is building an Apple Watch app as a partner to an existing iOS app. In our iOS app we already have a subscription model set up. What we'd like to do is have the Apple Watch app only be available for our subscribers, but we aren't sure is Apple will allow this or if we'll get rejected on app store review. Much searching has not yielded any insight into this topic, so throwing it out to the masses.

Has anyone tried to have a subscribers-only Apple Watch app?

Not to rehash a 2 year old topic, but did you ever figure anything out around this?

Unlock Apple Watch app with iOS app subscription?
 
 
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