Heh. I think that was one of the first things I ever went down a rabbit hole to understand on The Internet. And it eventually led me to learn that with just a bit of yoga (which you should do anyway since it is a great way to improve flexibility and general muscle health) you don't need to remove the rib. Admittedly, I have too much of a "dad bod" and a "beer gut" these days. But... it is totally a thing.
Feels like sucking a dick (which is fine if you’re into that, which I am), but with a lot of back and abs discomfort, which I am definitely not into.
But yeah it’s not actually super hard to do, just needs a few weeks of practice, and maybe a slightly lower body fat percentage so you aren’t getting in your own way.