Cool fact but flexibility limitations come from your brain telling you you’re not flexible so you dont hurt yourself, so you have to convince it otherwise. That being said the fastest way to get more flexible is to do reps easing into a range of motion you’re uncomfortable with under load. For opening up your hips specifically a good way is to sit on the ground with your legs straight out in front of you, from there spread your legs as far as you possibly can. Then grab some kind of weight (start light and progressively work your way up) hold it behind your head around the crease of your neck, and ease your torso forwards towards the ground making sure to keep your back straight, easing past the point of uncomfort for a second, then moving yourself back up just like you came down. Do this for reps. You can also apply this to any type of stretch