This version of the glute bridge is a great corrective exercise for teaching the body the sequencing and synchronization from the ankle to the lumbar spine that is associated with triple flexion and squatting.
It will certainly challenge dorsi flexion in a pseudo closed chain environment as the knee moves over the toes. There is feedback from the wall and load placed into the wall, but no vertical forces acting on the joint.
The body gets comfortable with relative lumbar flexion in an unload position because it has to go through that motion to get the buttocks of the floor. The beauty is both the novelty and very limited load placed on the spine. So even those with lower back pain will find this a helpful exercise as it reduces the threat.
Additionally, it helps create some separation and distraction of the tissue at the thoraco-lumbar junction. The upper part of the body is fixed on the floor as the lower part moves away, creating the distraction.
Put it to good use and tell us how you did!