So far it sounds like Gunn is looking at All-Star, with Action not even being mentioned, I don't think? It might be an influence who knows, and if so...
Definitely, plus it's a way to feature a weakened/more human Superman for a portion of the film without having to resort to The Green Rocks of Death...
Precisely. We won't get the full story no matter what DC does, even the MCU doesn't cover everything and they've been much better at covering ground...