Post 9/11 you could get a waiver from the ticket counter to escort someone thru security all the way to the gate. Dunno if that's a thing anymore, but I had them print out a paper and showed it at security several times in the mid 2000s.

A gate pass is a thing to pick up or drop off people who will be flying as unaccompanied minors. I don’t what other circumstances allow their issue, but when I did it a couple years ago, everyone seemed to know the process, so it’s not that rare.