Just met it today and would like to use it…
My first thought is that there could be an AMP template to be made but that wouldn’t be really feature that Grav could have, would be better to have a plugin that transform the actual template to AMP site as much as it can and gives the validation hints in an admin page or directly in the site’s source code with html comments for the webmaster to resolve.
Your ideas?
+1
+1
Looking forward to someone writing a plugin so I can check this out 
+1