I’m not sure about this given for instance IK warping feature was never released among other areas even though they are used in production they may have working internally so stating that everything is released to the public as they are at Epic could be a conflicting statement.
Regarding PUBG I have heard (correct me if i’m wrong) that they had invested in the tech to a degree and then Epic implemented it in Fortnite which resulted in a clash behind closed doors.