I got the pigeon stretch suggestion from https://www.medicalnewstoday.com/articles/320589.php, where they claim it's useful for prevention of illopsoas bursitis. And I may be doing a rather imperfect stretch, but I can definitely feel something loosening on something that starts in my lower back and goes through my pelvis before ending in my upper inner thigh. I walk a bit straighter afterwards, too.

To be honest, I'm not 100% sure what it does, only that it works, and I know very little about stretching, so I'd welcome any suggestions!