Which Oculus 3 is the Best Bang for the Buck?

I'm looking at getting an Oculus or two Oculi for my kids (11 & 14) for Christmas, so I have some time to buy. I'm trying to decide, and partially why I'm posting here, what the best route for me to go is.

Would it be better to buy a single $500 Oculus for my kids to share or two $300 Oculi for my kids to have independent of each other?

Besides the obvious sharing issues with a single Oculus, what are cons of having a single Oculus? What are cons of two Oculi?

Are games downloaded/online only? If not, is there a proprietary type of SD card (similar to Nintendo Switch) that can be interested to the headset?

What are the hardware specs - besides storage capacity - of the all Oculi? Does the $500 one have a better processor, RAM, and resolution over the cheaper models?

Sorry, I know these are basic questions that can probably be done by doing a Google search, but reading people's opinions vs reading a spec sheet have different impact.