It is my hip flexor(s) that are tight.

A friend of mine who is a massage therapist/physiotherapist showed me a super-friend stretch for this and we realized my right leg is not even near the left leg in “mobility” and it hurt so bad.

At the moment I can’t even squat cuz it hurts when getting deep into my squat, it feels like the hip is getting impinged in that.

So my question is, is there any good stretches I can do by myself?
I can’t always do the superfriend-variation of this.

Btw. The reason for my stiff hip is that when I’m standing at work is that I am leaning towards the right, which I think made this shit even worse.