The Shin Box (or 90/90 position) improves internal/external hip rotation. Adding the hip raise strengthens the glutes. Adding the overhead lunge portion of the getup makes this a complete lower body mobility and activation sequence.
Once you can do this with your bodyweight, add the overhead single-arm dumbbell hold progression to dramatically challenge your core stability and shoulder mobility. You can even add a lateral hinge for greater thoracic spine (upper back) mobility and oblique and lateral hip strengthening.
I'm doing the demo on my weak side with just a 25-pound dumbbell and it's pretty challenging. You can see I have more work to do in maintaining full overhead arm extension, especially towards the end as the TUT (time-under-tension) accumulates. Consider starting with just a 5-10 pound bell, your bodyweight, or even a shoe resting on a clenched fist.
I like to set the clock for 5-20 minutes and get max quality rounds of 1 rep/side. You could also do 1 rep/minute switching sides each minute for time. Or just hit 5-10 reps/side. There are lots of options to play with so just pick one and get it done.