How long does sperm live inside anus, and what happens once it leaks? can you get pregnant out of it?

It dies in minutes when not inside the favorable environment of the female vagina. The toxic effect of fecal debris is quick. A female having sperm leak from the anus is unlikely to ever have them be alive and capable of making the long trip needed for conception. The risk is not zero but close.

Anal intercourse will not result in pregnancy, but you can get STDs and anal incontinence from trauma to the anal sphincter. Get HPV vaccine. Wish you good health! Safe sex: https://www.hopkinsmedicine.org/health/wellness-and-prevention/safer-sex-guidelines