I'm also trying to express some sort of integration of player contribution with GM contribution under the premise that the basic trajectory of play is set by the GM. This is what Edwards used to call "participationism". I think that that's the closest thing we have, to date, as a "technical" label for Critical Role-ish play.
Right....yeah, I was leaning toward that with my comments about engaging with the ideas of others. For players in 5E D&D.....at least as far as the games I've been involved with.....the GM is coming up with the bulk of the fiction. Even when the GM actively takes ideas and content offered by the players and then weaves them into the game, they're still the one designing the bulk of things. The game is GM driven as designed, and even games I see that do as much as possible to shift that can really only accomplish so much.
Engage with the premise and with the ideas introduced by others.
And I think it's something for which (i) good advice is needed, and (ii) the old chestnut "You can do anything your character could do as a person in the fictional world" is unhelpful and even misleading.
I tend to think of that as pretty useless advice, in most cases. I get the idea of promoting that there aren't the typical limits such as those we'd find in a video game, but there are still limits. One being that this is a group activity, and the game will ultimately be about the group more so than any individual member.