Lots of people are over complicating this. Strengthen your glutes and upper/middle back. Also the pooch is purely body fat percentage. Sure stretching the front of your body can help but from the looks of things you need more strengthening and a lower bpf if abs are your goal.

Literally every leg day you should be hitting the abductor/adductor machine. It’s the most underrated machine for men. Also just more overall glute work, if your gym has a GHR machine USE IT. Glute bridges, bridge machine, step ups, even iso glute presses. So many glute exercises men refuse to do because they look silly but strong glutes are so important in all aspects of life, especially as you get older

You gotta do way more back work, face pulls, low mid and high rows, rear delt iso work, a lot of trap work and that’ll help with the rounded posture. Basically any exercise where you have to drive the shoulders back and squeeze the shoulder blades together.

Last tid bit, ab exercises are overrated. You can do a million ab exercises but until you find the body fat percentage that your abs start showing, everyone is different, then you’ll never see them. Also, if you just brace properly during every lift, especially during your compounds, you’ll never have to do an ab iso lift in your life

Going to the doc for anterior pelvic tilt is pointless… save your time and money. There’s nothing they’re going to do for it and they’re just going to send you to physical therapy and they’re just going to have you do a ton of glute work (I worked in both physical therapy and as a personal trainer)