What annoys me the most about these exercises, is when an expert makes them look easy. It looks like it wouldn't be a big deal, until I actually tried doing them, realizing how weak many of the muscles I have are to deal with these types of moves.
Well, the same case was for me with pull-ups. And let me tell you that doing static holds and negative variations of these exercises help a lot with the progression.
You literally just push into the ground and flex your shoulder. Fairly simple but what lifts the hips. It's probably not a technical cue that's gonna need. Rather, you just need more strength.
There’s no one-size-fits-all answer as you can adjust the intensity of pike push-ups. As a general rule, get really comfortable with multiple reps with sound technique + feet elevated. Also get very comfortable with a wall handstand. Then you can progress to partial wall HSPUs and gradually increase the ROM. This way, you can systematically ease your way to full HSPUs and build confidence with each progression.