Cook hip-up
That's the idea, but the non-working leg should be held to the chest. Small ROM. Drive through the heel.

Single-leg DL
notice that the knee is not locked, but should be bent about 20 degrees.

Stability ball hamstring curls w/glute bridge
If that's too easy, single-leg is a lot harder.

These will work for specific glute and ham strengthening. Also, if your PT didn't teach you exercises like these, get a different PT.

The problem with just doing lunges to try to address hamstring and glute weakness is that glute insufficiency is common, leading to synergistic dominance of the hamstrings, which makes exercises with relatively high loads and requiring strong hip extension painful in the hamstrings and the hamstring portion of the adductor magnus, because they're really not nearly as good of hip extensors as the glute max. What I've seen in clients is that when attempting lunges, they shorten the stride to shift the work back to the quads; this is doubly problematic because the quads are also inhibited by tight or overactive hamstrings (altered reciprocal inhibition), and the lunges are garbage. With a gradual progression to a longer stride, as well as targeted hip-extensor strengthening, the lunges get a lot better, and a lot faster than just simply doing lunges and hoping for the best.