Everything you can do on Nostr you can do the same thing on Pubky (if you want to). You could essentially port the entirely of Nostr to Pubky, thus taking advantage of PKDNS, if not for the incompatible curves.

The nature of PKDNS means everything on Nostr is a subset of Pubky and not the other way around. PKDNS is like a third dimension, where as for Nostr signed indexes, lists, drives, folders and boards all still exist in the same two dimensional space as everything else.