Could you show us some examples of AMP sites served from Cloudflare (and not the Google AMP cache) that show up in the Google AMP carousel and get the AMP logo in the Google search results?
Maybe they don't follow their own docs and there are sites out there not cached in the Google AMP Cache that still get placed in the carousel. I have no way to prove that without being able to test every single possible search term (plus all the other variables like location which affect the results).
And yet, you only get a ranking boost if you allow Google to cache your page on their CDN. You can not run your own modified version of the AMP js, or run AMP’s js from your servers, or opt out of being cached by Google’s CDN and get the ranking boost.
To quote the AMP specs, a page is only eligible for showing up as AMP in search if it