It would be interesting to see some data on the impact of masks in Scottish schools. Anecdotally, covid ripped through dd's year group in school and she and most of her friends caught it. Same age nephew in Scotland didn't catch it when a couple of his friends tested positive, and neither did many of his other friends. Of course, the plural of anecdote isn't data etc etc, but I'm yet to be persuaded that masks have no impact whatsoever. I do think the weird halfway house of wearing them in corridors but not in classrooms is pretty pointless.
According to dd, it isn't a big deal for the kids themselves. There will be a few who will struggle with it, of course, but the vast majority are probably more than capable of adapting.
DD really doesn't want to do online school again, so even if masks only make a little difference, I think she'd gladly wear one. I agree that there is a bigger problem in primary schools where none of the kids will have been vaccinated.