[Closed] Fitbit Charge 3 or Garmin Vivosmart 4 - HRV, spo2, sleep tracking?

Looking for a new cheapish smart watch to replace the Xiaomi Amazfit Bip AppleWatch knockoff I have. I think I've narrowed my search down to either the Charge 3 or Vivosmart 4.

I don't need it for fitness activity tracking, as I use a Wahoo ELEMNT + Wahoo HR strap for that. This is more general fitness metrics tracking.

Key features I want are:
• 24/7 HR monitoring
• Resting HR reporting (I currently do this manually)
• Night-time SpO2 monitoring
• HRV monitoring

I think both devices do this, they are similar in price (the Charge 3 is a bit more expensive), so it just comes down to overall ownership experience. Thoughts from owners of either/both devices?

Also - I've read that the Fitbit won't synch with Apple Health (I'll be pairing with an iPhone) - not sure if this is a deal-breaker for me, but would be a nice-to-have.