@Goffi not that I am aware of in the sense you are referring to it.
I am co-maintaining the #activitypub developer + protocol apps watchlists at https://git.feneas.org/feneas/fediverse/-/wikis/home
Regarding extensions we are setting up a FEP process:
And I proposed a more non-technical Fediverse Futures initiative to elaborate business domain extensions:
Server run by the main developers of the project It is not focused on any particular niche interest - everyone is welcome as long as you follow our code of conduct!