Nips should be published as their own nostr kind, client devs should publish signed collections of the NIPs they incorporate. Then you (and others) should make a website that lists all NIPs, along with compatibility chart of major clients that incorporate it, and those that don't. Similar to the firefox browser compatibility table on the CSS docs. So instead of having an authoritative list of "official" NIPs, you have a much longer list of NIPs, but on each one it shows client compatibility so you get an idea of your reach.