AMP has been discussed before:
https://forum.x-cart.com/showthread.php?t=73673 and then again recently here:
https://forum.x-cart.com/showthread.php?t=75011&page=2
Out of interest, we created an AMP page (hosted on the same domain, but not part of our XC5 store). It's massively faster than XC5 every single time, but it's static content only so it doesn't have any e-comerce functionality other than links to the XC5 store. It's therefore, not a like for like response time test. We thought that an XC5 AMP module (for use on XC5 static pages etc) would still be a very good idea at this stage (Wordpress mimic). Future 100% AMP XC5 stores we can't see happening though...