The movement can be considered a bodyweight exercise similar to the military press, while the regular push-up is similar to the bench press.
The primary muscles used in the handstand push-up are the anterior deltoid, middle deltoid, posterior deltoid, pectoralis major, upper trapezius, and triceps brachii.1
The handstand push-up is measured in the Men's Gymnastics Functional Measurement Tool (MGFMT). According to one test on competitive male gymnasts in the United States, those competing at Level 4 averaged 3.0 handstand push-ups while those at Level 10 averaged 15.7.2
Johnson, Abigail; Meador, Melanie; Bodamer, Meghan; Langford, Emily; Snarr, Ronald L. (2019). "Exercise Technique: Handstand Push-up". Strength & Conditioning Journal. 41 (2): 119–123. doi:10.1519/SSC.0000000000000427. S2CID 56807126. /wiki/Doi_(identifier) ↩
Sleeper, MD; Kenyon, LK; Elliott, JM; Cheng, MS (2016). "Measuring Sport-Specific Physical Abilities in Male Gymnasts: The Men's Gymnastics Functional Measurement Tool". International Journal of Sports Physical Therapy. 11 (7): 1082–1100. PMC 5159633. PMID 27999723. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5159633 ↩