A 1 M solution of pure glycolic acid has, due to the lower pKa, a pH of (estimating/guessing here) less than 2 because acetic acid has about 2.5.
pKa only matters if there is a buffer present or a salt used but not in case of a pure acid. Given that you intend using diluted glycolic acid, the pH might slightly differ. You easily get down to a pH where nothing (at least nothing you commonly encounter in human inhabitable surroundings) can grow but then again, your skin might not be very happy… unless you use a strong enough dilution to get something which can be ‘buffered away’ by whatever is on your skin (many constituents of NMF buffer nicely).