Parent web app could run relay conns & event storage and child apps could communicate with it over postMessage
This is a very good idea:
Not because of the way nostr:npub1l3cgtsurhfchg4cyhhqudm70074sr96srhje330xc5m6czej5n9s9q6vs2 frames it, but because it fixes the problem of web clients being what the user wants them to be and truly representing the user and not some new malware everyday loaded from a URL controlled by someone else.
Discussion
Yes, these are good ideas. These features could be window.nostr.napp optional add-ons.
Currently, each app handles its own ws connections and local storage as usual but the good thing is it can always consider there is always only one user, always the same one. No need to code for multi-user. While the 44billion.net is multi-user, the napp sees just one.