New GWM with BB, GFB and true strike

is it correct to understand that the new GWM no longer work with BB,GFB and true strike since GWM states it have to be part of the attack action?

For the first benefit, I think so, but it should interact with those weapon-based cantrips if you cast the cantrips as part of the Attack Action thanks to Eldritch Knight's War Magic, College of Valor Bard's Extra Attack, or Bladesinging's Extra Attack.

EDIT: I got ninja'd with a superb answer! kudos to wagnarokkr!

good catch with eldritch knight