For holding keys you'd need to look at IPFS + shitcoins + DID stack.  Though DID is creeping in to alot of places.  Tons of apps there, but I consider that proprietary.  Yet there is still innovation.  When you see games get to 10 million users in a month on other platforms, you realize that nostr as big competition.  You can make the argument it's apples and oranges, but there is an intersection.  Nostr has legit competition in social, and legit competition in payments.  We of course know it's proprietary shitcoins, but the users dont.  IPFS and protocol labs have their feet in both areas with investments in activitypub projects, bluesky and also their own premined tokens.  Even just looking at the old Luna project that went bust, had a very impressive set of apps.  I dont think nostr has every imaginable app.  There are few social games (e.g. words with friends), few prediction markets, few smart contracts, few market based apps.  Lots of good twitter clients, blog clients, zap stream is great, torrents.  But we've not replaced reddit, facebook, netflix, google, dont have cutting edge AI (ok maybe openagents).  There's not a really good chat app that competes with whatsapp/telegram which quickly goes to millions of users.  Unclear how far the infrastructure can go.  There is legit competition on all fronts, nostr is a niche space with high R&D, but plenty of folks doing lots of stuff out there.  Will be fun to see how it evolves.  What is true is that nostr is in the 1000s of users, and competitors are in the millions of users.