The other day, Google announced a new penalty for AMP pages that have partial content with read more links that take you to the full content. We called it the AMP teaser penalty and Google said it will instead just rank your non AMP page over your AMP page and thus you won't be able to show up in the exclusive AMP sections.
This was their example screen shot:
But there is a way around this, if you want... You can link your AMP teaser page to an HTML teaser page, which then has the read more. So as long as your AMP canonicalizes to an HTML page that has equivalent content, you are good.
John Mueller from Google answered this specific question on Twitter:
it's compared to the canonical page - so if they don't do it there, they shouldn't do it elsewhere. (It wouldn't be equivalent if the pages don't really provide the same content / functionality).
— John ☆.o(≧▽≦)o.☆ (@JohnMu) December 5, 2017
Now, of course, this is not recommended. Google won't see your full content and you won't rank as well since the full content is not there. But if you wanted to just mess with Google, in exchange for you messing with your own rankings, sure, have fun.
Forum discussion at Twitter.
