The problem is that I don't want to annoy the current operators to make them update their stuff, and it would risk splitting the ecosystem, making it too complex and so on.
But If someone wants to run an alternative central, perhaps they could do just GitHub, Apple and Microsoft and not Google? With a different set of operators? I don't know, to avoid conflict.
Someone else could run one that does phone numbers and raw email (not supported in the codebase, but should be easy to add, although SMS costs money and these things are directly painful to me so I don't want to touch them).
Someone else could run one that doesn't integrate with anything, just generates a secret and tells the user to store that, which they can later use to recover their nsec or login in to other apps. How this could work exactly is yet to be discussed.