Mezuzah for new home

Hi everyone! My best friend and his wife just bought their first house (yay!) and while I’m home visiting next week, I wanted to bring over a housewarming gift. Among other things, I was wondering if it’s appropriate for me to gift them a mezuzah? I’m not Jewish so I wasn’t sure if it had to come from someone within their faith, or if it should be given through other more “official” means? Any insight would be lovely, thanks!

Edit: I’m reading elsewhere that maybe a gift certificate to a Judaica store might be the next route to go, so I will look into that!