It’d be interesting to have Pietro’s white hair be about more than just his relationship with mutanthood. I know this is focused on Pietro being mixed (which is important too, the fact Pietro mirrors Erik and Wanda mirrors Magda. No matter what retcons say..) but Pietro being albino is a popular headcanon I can see the merit of, while the canon reasoning was him being a mutant (No Matter What Retcons Say), which all can work well with telling a story about a mixed Romani man who’s features are being scrutinized by the people perceiving him and his twin sister at once.
There’s the fact he distrusted Magneto, because while he did save the twins from being persecuted and claimed it was fate, he coincidentally hides his hair (a point of tension for Pietro) under that helmet.
And when Pietro dreams of the night his mother abandoned them, he projects his feelings of being rejected onto her.
He’s never seen Magda before (and this is stylistically fantastical) but he doesn’t subconsciously imagine her having his hair color, and is a subtle detail that supports the reading of Pietro thinking their mother saw he was different and bailed. Because that’s what he’s used to.
It’s also, later, one of the reasons he suspected Magneto to be related to him—even if Erik’s white hair isn’t likely an effect of mutation.
It’s heavily implied to have whitened over time for Erik; I theorize from stress (Have you ever experienced solo tanking? I can’t blame him lol) because of how he was depicted with black hair as a child in the one comic that’s about his childhood (See, Magneto Testament) and yet had white hair as a young adult. Since there isn’t any story I know of personally that says Erik stood out for his white hair (he’s faced discrimination, yes, but not for the white hair), unlike Pietro. So I am inclined to believe it’s seen as a natural and gradual change that, even more coincidentally, makes him look more like Pietro.
Pietro canonically feeling like an outsider for his features parallels the experiences of mixed Roma living in Eastern Europe—and while I doubt Sean McKeever specifically intended it beyond the mutant aspects of Magneto being Quicksilver’s father—it means telling that story someday would still fit seamlessly with Pietro’s character.
Whether it’s because he’s mixed, a mutant, or has albinism, Pietro will always be judged for looking different.
(All the panels are from Avengers Origins: The Scarlet Witch & Quicksilver)