Your best suggestions to implement Google AMP ?

Try searching this forum for Ampproject because I have posted quite a few solutions as to how I implemented Ampproject and CodeIgniter.

My first post was way back in March 2016.

Remember to install the Ampproject browser plugin because W3.org validations do not work.

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But it doesn't really help me because it just explains what AMP is. I'm rather looking for a solution to convert HTML to AMPHTML easily. For example through the cache output, making another AMP cache, through a converting library or something like that.

because when you have a project with millions of page, you can not really just do it manually...

Was CodeIgniter used to generate the "project with millions of pages"?

If the above is true then no doubt a Controllers would have be used to extract data from a database Model and passed to a View to create the final web-pages. 

If the above is true then the same data can be used to generate am AmpProject compatible View.

Have you actually used CodeIgniter to generate a valid AmpProject web-page? 

If the generated web-page does not conform to the strict validation rules then Google will not optimise the web-page and not give it preferential SEO treatment.