I agree that they knew putting Evan Peters in as fake Pietro would cause buzz. They could’ve just cast idk, someone like Zac Efron instead. But they knew Peters would cause speculation about whether he’s real or not.
But at the same time, Marvel never promised anyone that a multiverse was gonna be introduced in this show. Feige has been very consistent in saying they’re not introducing the X-Men anytime soon, and outside of Ryan Reynolds, there’s been no indication that Marvel is keeping anyone from the Fox universe.
But I think casting Evan Peters was just fan service at the end of the day, they could’ve cast anyone to play a fake Pietro but they knew fans would be excited for him