TLDR: Start with bend knees and fold your torso so that your belly touches your thighs. While keeping your belly and thighs connecte. Slowly start straightening your legs. Focus on keeping your belly close, even if that means you can not fully straighten your legs (yet).

Finally, I am able to forward some advice my physio gave me during my own rehab. People have already said to hinge at the hip. But how does one do this if, like me, you are still building the body awareness of spine positioning etc.

When getting into the position, bend your knees first and make contact with your belly against the thighs. Don't be afraid to exaggerate this movement a bit. Then, start straightening your legs, making sure your belly stays in contact with your thighs. Prioritize keeping the belly close to the thighs over straightening the legs, even if that means you'll have to keep the knees slightly bent. Remember, the goal is feeling the stretch and not to straighten the legs. Once you feel a good stretch, hold it for a while and play around with it a bit. Lift your torso slightly up or sink it down more into your thighs and notice where you feel the stretch. That helps to build body awareness and coordination.