Improved version of handstand push-ups

First do the starting position of ordinary push-ups, then lift your feet to the top of a chair or a box, put your hands on the ground and move back a few steps, with your buttocks facing the sky. Keep your upper body in a straight line.

Then follow the standard of doing push-ups, keep the upper and lower body at a fixed angle, bend the arms, bring the head as close as possible without touching the ground, and then straighten the arms to return to the original position.

How many can you do each time? The movements must be standard.