Thank you so much, I'm really happy to hear you find it impressive!
Yes, it's most likely a browser issue, as not all browsers supports AR features. ARCore is maintained by Google, so any chromium based browser is likely to work. Such as Brave, which I just tried to make sure it's working.
With that said, it's great that you bring this up, as I should definitely add some kind of warning when an unsupported browser is used.