I think the entire Commonwealth knows what's what for the younger son. It's 'private' and that means friends and members of charities. No stuffy olds that neither of the Bridal Couple knows etc. If the odd ex or current politician or churchman show up, it's personal.
In some cases, the faces will be familiar, in others, not so much. But Harry's family is huge, Meghan's is not. Harry's friends are a select few, Meghan's on the other hand, may very well be a lot bigger.
I remember when Victoria and David Beckham finally at William and Catherine's wedding the commentators had been wittering about it since the first guests arrived and They found that for the most part, it was first in best seats. Theirs weren't because they were thinking celebrity not royalty. (oh hats! hope there aren't any fascinators that look like they've been bolted to the forehead like Victoria's did).
As for bridesmaids in white? Lady Sarah Chatto's is still my favourite private royal wedding party. All that white chiffon and flutterings of swans . . .
https://visitbritainnordic.files.wordpress.com/2010/12/lady-sarah-chatto-wedding-shot.jpg