Apple

Ye I think so

You’ll get steps in the Health app but you won’t get your rings in fitness and unbelievably nothing will transfer back to your watch, that’s a one way street.

Yes

Sure does.

It does in a less accurate fashion. It may also fail to show on the Fitness app but it will show up the combined data on the phone’s Health app.

It won't contribute to your rings.

If you have an Apple Watch your iPhone won't add data to the Fitness app