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There are 3rd party websites that provide a JS that uses their proprietary system, but that scares me because they may or may not be accurate, or even around in a few years/months/days.
You're looking for Option E) aren't you?
So G definitely has the technology to recognise the mobile version of a site and serve up the correct url in the mobile SERPS.
Annotations for desktop and mobile URLs
To help our algorithms understand this configuration on your site, we recommend using the following annotations:
On the desktop page, add a special link rel="alternate" tag pointing to the corresponding mobile URL. This helps Googlebot discover the location of your site's mobile pages.
On the mobile page, add a link rel="canonical" tag pointing to the corresponding desktop URL.
I'm not looking for any "magic"