In the end, what it all boils down to is that it doesn't matter one iota if Harry's bride is from the US, Canada, Timbuktu or the Seventh House of Betezed or what the popular opinion of his bride is. If and when Harry decides to marry, it will be his choice and his choice alone and the marriage will happen with the blessing of his monarch.
Everyone else on the planet may have opinions and that's their right to but to think that a marriage would not happen solely because of an opinion of the general population is grasping at straws.
Although I don't disagree with you, I think popular opinion matters to the British Royal Family and, indeed, to any European royal family nowadays. Meghan may in the end prove to be a popular royal bride and royal spouse, or she may not, but, in either case, I wouldn't ignore the importance of public opinion about her in Britain and the broader Commonwealth.