Here’s showrunner Jac Schaeffer talking to EW about it:
“There were early conversations [about Hulkling],” Schaeffer said. “[Eddie] was originally called Teddy because we were looking at the artwork and thinking about that. That was a Marvel decision to not have him be Hulkling for the purposes of our show. Within our show, he is not Hulkling…but we pivoted to Eddie because he is named after a person that is important to the writers’ room. It wasn’t sort of teasing the fans, it was one of those lovely tributes to somebody who matters to us.”
That really was one of the good things about Agatha All Along. All you really need to know is that we open with Agatha imprisoned in her own mind after trying to manipulate an extremely powerful witch who’d gone mad with grief. The rest is optional if you’re willing to roll with a few otherwise weird ideas that arise out of the MCU-ness of the show.
I guess? I would really struggle to suggest watching Agatha All Along without first having seen WandaVision. Despite the different names it’s really a season 1, season 2 situation.
I think you could survive without Multiverse of Madness since the first episode of Agatha clarifies that Wanda is dead, but WandaVision sets up so many things that are further explored in Agatha.