But saying that
xbps-srcis like the AUR is very misleading because it lacks the "U" part.
It is misleading because AUR is a repository, but xbps-src is not. It is a tool like makepkg in arch. One could argue that xbps-src is a more advanced tool as it also acts as a package manager itself. A repository that is most commonly used with xbps-src is void-packages which is maintained by void teamm one could build a repo for xbps-src like aur, but to my knowledge it has not been done and is unlikely to succeed any time soon due to a smaller user based compared to arch.
They can just block them like pirate websites.