Details surrounding Carrigan’s role in Bill & Ted Face the Music are being kept under wraps for the time being.
It should be noted that in the Bill & Ted comics, which not sure if that’s considered canon, Missy, who has been the step-mother of both Bill and Ted, ended up with De Nomolos, and they had a son.
And today we have a rumor that Carrigan’s “relentless” antagonist may be the son of William Sadler’s Bill & Ted’s Bogus Journey character, Death.
Also, in this current timeline, De Nomolos would be much younger than we see him in Bogus Journey, so Carrigan could even potentially be playing a young De Nomolos.