“Continue”? They mentioned him once.. and that’s it. Not really an exploration of their relationship

If Evans Peters does appear in the show I don't believe it will be as Quicksilver. What's the point, the show has given his powerset to Vision in WandaVision. But Pietro Maximoff (even though Evans played PETER Maximoff in the Fox films), is a possibility. It's sort of messed up to have a different actor, besides Aaron Taylor-Johnson playing an adult Pietro in a MCU film but we have to keep in mind THIS Pietro wouldn't be real.

My guess we'll get a younger actor to play a kid Pietro and possibly adult Pietro with Wanda in present day as well as the Winter Soldier flashback sequence hinted in a promo. If it ends up being Evan Peters, so be it. He would be revealed to be a fake Pietro by series end anyway. I just hope Aaron returns for real in Doctor Strange 2 alongside teenagers Tommy & Billy and Vision. This way Wanda can get a happy ending to her story. Perhaps resettle back in Westview and actually get the idyllic life she wished for in WandaVision. At least, until Marvel Studios calls upon her character again for a future story.

I'm still calling, if Evans Peters appears, he'll be Mephisto posing as Pietro. A villain in plain sight.