From the ground we have a couple options to get the hips moving in internal and external rotation, start slow and smooth and when you feel you can control that that articulation lift up off the ground and control back down with either bodyweight or an exertnal weight
From the ground with a little more of a stationary approach really trying to articulate the femur in the hip socket. We can load this movement simply with the friction of the ground or something like a furniture slider, drag you heel on the ground while externally rotating the hip.
From a standing position here getting the foot more involved for that foot and hip connection think about cueing the foot into the ground and having it find the hip. With these think about keep the femur of the down leg stationary while moving the pelvis around it.