What is the risk of hiv from stepping on a hypodermic needle? also would you feel it pierce your skin?

Remote: Were you wearing shoes? If yes, there is no risk. Unless you have neuropathy, you would feel a needle pierce your skin. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Drink enough water daily, so that your urine is mostly colorless. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex, if you have sex.

Little or no risk: This is one of those theoretical risks that are very rare. I'm not aware of any reported HIV cases, ever, from stepping on a needle or otherwise being stuck with a needle in the environment. Most people would be aware, but not necessarily if distracted. People often get minor cuts or other injuries that they don't notice until they see bloodlater; it's probably happened to you! Still, no worries.