Has anyone seen any comment on this with regards to GOG?
Almost certainly the same, 10 A.M. pacific because otherwise it would divert from Steam.
Honest question, why do you think that? I mean, of course it would divert from Steam then, but Swen quite clearly said, they'd have preferred an earlier release time, but Steam wouldn't let them due to wanting manpower at time of release.
GoG has their people in Poland, so they can have their manpower for release ready at [earlier time]™.
That's why I think there's at least an however small possibility.
Or does Steam contractually force publishers to nowhere release earlier than on Steam?