For one arm standup push-up if you have push-up handles then you use one of them and the other arm on the floor and you alternate this basically puts more of th

For one arm standup push-up if you have push-up handles then you use one of them and the other arm on the floor and you alternate this basically puts more of the load on the arm that is on the floor while providing some support. You can also use a palm on the floor and forearm on the floor if you don’t have the handles or just use a book/anything to elevate one arm to reduce its range of motion and to allow you to transfer more and more weight to the other. But for hand stand push-ups you have other ways of progression such as curling your body to reduce the center of mass and to isolate your arms, chest and shoulder more from your back and core. I generally avoid one hand anything because it’s too easy to get injured which is one of the main issues with body weight. Most people won’t be able to lift enough weight to get injured and unless you are doing singles/doubles you are more or less safe. With tings like one armed handstand pushups it’s way too easy to get to a point in your range of motion where you have absolutely no chance of holding that weight in fact it’s rather easy to do it with normal hand standing pushups. There are safer options for shoulder/delts dominated pushups than hand standing ones.