Hello,
i just launched the first iteration of https://www.eziga.de built with KirbyCMS and Google AMP only. It was pretty easy to add custom kirbytags for AMP’s required markup and get most AMP components running very quickly.
In the future i am going to add some IO functionality, so users can interact with the site, have a little messageboard and comments or such. have not looked into that as much, but , as it seems, that it would require some custom things to get it running in kirby.
it took me like a week from start to finish without having touched AMP once before. so if you want a basic website running AMP, kirby is definetly one of the easier CMS to run with.
if you plan to get a normal html site alongside a seperate version w/ amp, i think you should pretty easily get started with a custom page method, explained here.
also, if you are looking to get json running in kirby, it is a bit messy, but works just fine.