Nostr is not comparable to Bitcoin Core because Nostr is not a dynamic code base. It's a set of specifications. It's more like the Whitepaper.
Discussion
Nostr is not a FOSS project, but most of the implementations are.
Nostr disintermediated the development process. Most similar efforts (Linux, Bitcoin, MySQL, etc.) bundled the protocol with the Core implementation of the protocol.
Nostr is inherently different, as it defines a protocol and leaves implementation completely open, so that we now have a bunch of de facto Cores (the various SDKs and larger Kind 01 clients).
This is an environment that can make it difficult to attract top-talent, as they tend to want to build for the base protocol directly, so that their name is associated with the strongest brand. Building on Nostr is more like building on a distribution of Linux, than on the kernel. Way less glamorous.
Also, building implementations requires some sort of business case and market research and social skills, and they tend to be bad at that; it's a different specialty.
The different Nostr Cores are like there's a bunch of Linux kernels or Bitcoin Cores written in different languages, by different teams, with different functionality.