If they are already using a CV1, I suspect they have a gaming PC capable of driving beatsaber. With a quest 2 you can wirelessly stream from your PC to the head

If they are already using a CV1, I suspect they have a gaming PC capable of driving beatsaber. With a quest 2 you can wirelessly stream from your PC to the headset to play any game including beatsaber custom songs. I've had Good experience with the latency on this setup, but I do have my PC connected to a 5 GHz router via ethernet and play in an area next to my router.