Meta Quest 2 (previously known at Oculus Quest) is definitely the place to start. One of the cheapest stand alone VRs. Can monitor activity on the phone app. I wouldn't go for the Quest 3 just yet as you don't know how your child will react to one. There's risk of motion sickness and beware of "VR Fog" which can make you feel a bit funny after you take the headset off. Takes some time to get used to. We got one a couple of years ago and honestly we've got our money worth, someone is always using it.