Here’s what I think is happening in the show. And, yes, this means there is a larger story, but it’s being developed subtextually. The key points will be clearer retrospectively, after the mystery has been fully unfolded.
Hiding behind spoiler fog, in the unlikely event this is accurate speculation and “ruins” the experience for anyone.
The miniseries is set post-Endgame.
The backstory is, Wanda didn’t want to accept Vision’s death. She retrieved his body and went seeking magical assistance in resurrecting him. The lost infinity stone turns out to have been critical to the gestalt of his identity, so she finds no easy answers.
Eventually, she was approached by a powerful mystic. I’m assuming this is Agatha Harkness, due to the comics connections. Agatha offered a deal where she will try to resurrect Vision, in exchange for Wanda bearing a child which Agatha will take custody of.
Wanda accepted the deal, but it didn’t work out for whatever reason: maybe Agatha failed, or maybe Wanda realized Agatha’s intentions for the future child were nefarious.
As a result, Wanda defensively manufactures a pocket universe, trapping herself, the incomplete Vision, and Agatha. The specific nature of the pocket universe is informed by Vision’s half-recovered programming; he spent a lot of time consuming media in an attempt to understand people, and that is now being surfaced. Essentially, Wanda’s attempt to pull Vision’s self out of his ruined body has wound up creating this false reality using his imperfect, and now fragmentary, conceptual model of human experience.
This would explain a lot. It provides a basis for the sitcom world. It explains why the Agnes character is so pivotal as a motivator/explainer/mentor to Wanda, because she’s actually Agatha. It explains the anachronistic racial makeup of the supporting cast; these are real people who have been pulled into the reality bubble. Some of them, like the “Geraldine” character, may actually have been deliberately inserted into the bubble, rather than being pulled into it by accident; she’s Monica Rambeau, and may be working with the SHIELD-adjacent group SWORD in an attempt to rescue Wanda from the outside. That would explain the radio voices and the injections of cross-reality elements, like the toy helicopter, which could be an adapted manifestation of a drone or an actual helicopter or something else from the outside.
Ultimately the key conflict will be Wanda’s refusal to let go of any hope for Vision’s return, versus her friends on the outside trying to get her to release control and return to the real world.
All of this is basically a mash-up of the “House of M” storyline with a bunch of other comics stuff. It’s not a direct point-by-point adaptation of anything, but it’s closely inspired by key developments throughout Wanda’s history as a character.
This predictive speculation does require some familiarity with the comics. However, if I’m correct, then all the necessary reveals will have been made by the end of the miniseries, and there’s nothing here that will demand extratextual comics knowledge after all the cards are played.
And if I’m right, then we’ll be able to go back through the first two episodes and see that there are lots of little hints being dropped as to the larger story, in terms of why Wanda and Vision are doing what they’re doing and behaving the way they are. I’m pretty confident there’s more going on in those first two episodes than what seems obvious from a cursory initial viewing.