I did watch the Legends show to catch up with these characters, but I did not find it helpful in the least. There is not really any actual backstory there, it's just clips from the movies they were in, which taken out of context, does not make their story up to this point any clearer. I think if you need a recap for these characters you are better off just googling it on the internet, which I eventually did.
I am coming into this with very little MCU knowledge. My Marvel viewing is limited to the Thor movies, the Guardians movies, Black Panther, 20 minutes of Dr. Strange, 15 minutes of Ant Man, and Peggy Carter. I have seen zero Avengers movies, so I don't know if this is for me because all of the easter eggs are lost on me, reducing it to a mediocre 1950's sitcom. I know it's more than that, but I can't even begin to speculate on what these clues represent. Unlike The Mandalorian which works for the casual Star Wars viewer because it's a whole new character, I don't think this translates as well for people not up to date on the MCU due to the long backstory on Wanda and Vision. Not sure I'm going to continue this one....