While most of the contributions I have seen are from Google on the browser side, they are trying to work through the standards process. Here's the first draft of the w3c standard: https://www.w3.org/TR/fedcm/

I know there's a later draft but can't find it right now. Will share when I do.

As mentioned in sibling comments I have seen are least on Firefox contributor and they are actively seeking input from identity providers.