In the Nordic countries tights are not a particularly gendered item of clothing. H&M is a Swedish brand.
Boys and girls, especially when young, both wear tights under trousers to keep warm in winter. Babies and toddlers also often wear just a bodysuit and tights at home / inside, like just casual wear.
My kids both wore pretty much exclusively tights, no socks, for the first two years and I have a boy and a girl. If the climate suits, they are much better than socks because they can't fall off or be pulled off.