Question on the free apple tv offer

The offer is for the first Apple ID that signs up on each device. It doesn’t matter who purchased them.

Only one offer per Apple ID and only one offer per family if you’re part of a Family Sharing group, regardless of the number of devices you or your family purchases.

Yes, either by redeeming the offer on 2 different Apple IDs, one for each iPhone, using family sharing and redeeming it on one Apple ID to then share it to the other Apple ID, or using the same Apple ID on both devices.

If you use the same an Apple ID on more than one device and redeem the offer one of them, the offer is automatically available on all devices using that Apple ID.

However, unless you own and use both iPhones, sharing an Apple ID is highly discouraged.