You wouldn’t concern yourself with the legality, if your threat vector includes the traceability of the phone number.

And regarding your (in this context) nonsensical privilege remark: I live in such a country. Yet I have used such numbers.

If somebody is that paranoid (or in a situation where that level of secrecy is necessary) they would not use a number that is traceable to them… So it doesn’t matter if they have your phone number or not.

he’s using google chrome

That answers how it happens. My guess is that he googled things relating to submarines or his browsing behavior regarding that game caused him to be grouped as potentially interested in submarines. If you are using chrome everything you do will be collected and used for marketing. No amount of extensions will save that since the browser itself is spying. If you want to minimize this happening you have to switch browser (brave is the closest to chrome) and stop using google for search.

That is not the point… The anger stems from Americans deciding they want something and then strong arming other countries into complying.

That is just so much not the point… The anger stems from americans deciding they want something and EU kissing their asses to cater to all their needs. Just the fact that this