In my head, we are overfocused on the idea that Evan Peters is Pietro in the Fox universe. I think it’s more of an Easter egg than anything plot related. I think, if it’s Nicholas Scratch, Scratch is showing his true face. And since no one knows who he is, no one is the wiser
I think if they could make him look like MCU Pietro, they would have. So I think he’s not looking “like someone” - Nicholas Scratch (or whoever he is) looks like Evan Peters in this universe
The biggest hole in this theory is the fact that we saw that brief moment of Pietro with gunshots. It doesn’t fit in my theory, unless it was just a moment of hypnosis to sell the theory.
Well, this week, Agatha says that Pietro was a fake who was "possessed" by her, which tracks with Pietro's dialogue sounding more like Agatha's character than the character played by Aaron Taylor Johnson. It's unclear, however, as to the identity of the person with Evan Peters' face and voice as Agatha is dismayed and jealous of Wanda's ability to create living matter and engage in transmutation at will (with these limitations also making it impossible for Agatha to make the impostor look like the Pietro that Wanda remembered).
It was also a shock to see that the Vision in WANDAVISION to date has never been the Vision but a simulacrum of some sort based on Wanda's memories of him with the actual Vision having always been in SWORD's keeping.
There is a really painful, agonizing tragedy to Wanda having experienced a horrific trauma -- the death of her parents -- while watching THE DICK VAN DYKE show. It's something I myself understand. Wanda turned to American sitcoms in her childhood for comfort; they brought her relief from the gunfire on the streets and the hunger and poverty and quiet desperation of her childhood.
This is something I really understand and relate to, having watched SLIDERS during a savagely violent childhood during which Quinn, Wade, Rembrandt and Arturo brought me a lot of comfort and relief -- until they didn't and the brutal cruelty of the world I knew outside SLIDERS seem to infect the world within the TV show as well.
And I can understand Wanda's wish to retreat within the world that brought her comfort as a child and to effectively write a lavish self-insertion fanfic for THE DICK VAN DYKE SHOW, I LOVE LUCY, BEWITCHED, FAMILY TIES and MALCOLM IN THE MIDDLE -- and to address her grief and loss in this context. However -- and this is very important -- one must use these safe spaces of conceptuality to fully confront one's own demons, regrets, fears and traumas, whereas Wanda has 'written' her fanfic simply to provide comfort and engage in avoidance and denial.