Wow! Great episode.
I enjoyed the fact they were able to retcon Wanda's 'origin' to show she always had latent mutant/magical abilities; and it the infinity stone somehow amplified what was there - meaning she and Pietro were the only ones to survive exposure BECAUSE of their mutant abilities. I also like how they finally gave her the moniker "Scarlet Witch" here.
It also in no way precludes Wanda finding out Magneto is her TRUE father. The one sad thing is it looks like they won't be restricting Pietro and reuniting the 'twins' (unless it's a part of the "Multiverse of Madness" Dr. Strange II feature film the Wanda character is going to be a part of.
And IF WandaVision is a lead in to that film - along with everything else in it - IF we get another major Marvel 'hero' appearing in the final episode, it has to be
Dr. Strange.
I also agree with some others here that (end credits in the previous episode aside WRT "Sparky"

); Agatha Harkness may not be the Villain here. If anything - back in 1693, she was found to be a 'Scarlett Witch' (and hence extremely powerful - which was why she was looking at material above her 'station' in the Coven in an attempt to better control said power); and that's why the Coven 9and her own mother were attempting to execute her because they believe that such power corrupts the person, and thus they ultimately use said power to horrible ends. Agatha (after 328 years) may still be trying to control/curb that impulse (or actually believe she has, when in fact she hasn't). My point being: Agatha believes she can, and she wants to be 'good'; but she keeps occasionally 'slipping up'.
In fact given what we now know about this entire situation, and the fact Agatha Harkness is shown to be a 300+ year old magical being directly involved (and perhaps drawn here when she sensed what was going on here and found Wanda at the center of it) - I'm surprised Dr. Strange (or Wong or some other powerful Earth sorcerer or sorceress ) hasn't already shown up to access and correct this massive magical situation - UNLWSS we find out Agatha is an agent OF Dr. Strange, sent for this exact reason.
I mean hell, in
Thor: Ragnarok, Dr. Strange was aware Loki and Thor had travelled to Earth and almost immediately contained Loki while he spoke with Thor to find the reason Thor brought Loki to Midgard.
In other words - if what Wanda has been doing IS magic-related, you'd think Dr. Strange would show up almost immediately given the power level of the magic involved.
But yeah, eagerly awaiting the final episode to see how they finish this aspect of the story.