Can people with specs easily use the Apple Vision Pro

Yes you can. If you are looking for a in store Vision Pro demo, the staff will help you to settle everything, you just need to bring your specs. If you are buying one, you will need to upload the subscription and pay extra for the Zeiss specs. Either way, your son can enjoy the Vision Pro

Be aware that Apple restricts use of the AVP to kids 13 and older. From the AVP support page: “Children under 13 years of age can’t sign in to Apple Vision Pro with their Apple ID. Children ages 13 years and older should be supervised by an adult while using Apple Vision Pro.” Very unlikely Apple would provide a demo for a 10 year old. No problem with the Apple Watch.