Marvel’s doing a What If? Cartoon, and even back under Lucas, they had the “Infinities” label to do something similar, especially in the Star Wars Tales comic series - Vader vs Maul, Indiana Jones tracking Bigfoot and finding a crashed Millennium Falcon with a deja-v-evoking skeleton in the seat and “Bigfoot watching from the sidelines, a random tale of a slave taking advantage of a clumsy Sith Apprentice to replace him on the rule of two, the first appearance of the woman who was Boba Fett’s wife...
I don’t see them doing anything as firm as retconning anything film-related.
But honestly, if I were LFL, I might consider starting something like Star Wars Tales on the basis that an ambiguously-canonical series would allow creators to do what they wanted without worrying about stepping on any toes for future films.
That’s the kind of thing that could maybe be used without regard to the Sequel Trilogy.