Transferring Apple Music 6 months free offer

I bought my wife Apple AirPods Max for Christmas, using the Apple Store online with my Apple ID. These came with a 6 months free trial of Apple Music, as my iPad keeps reminding me. I don't, and have not previously, subscribed to Apple Music, but want to transfer the 6 months free trial to her Apple ID so that she can use it on her iPhone; she does not have an existing subscription either.

Following Apple's instructions to redeem the offer (i.e., open her Apple Music app while the AirPods Max are close to her iPhone) does not bring up the offer in order to redeem it.

The trial has not yet been redeemed on any device.

Is it possible to transfer the offer from my Apple ID to hers so that it can actually be used?