When XSLT 3.0 tells a joke, it starts with "a JSON walks into a bar..."
https://github.com/Saxonica/Saxon-HE
FWIW https://saxonica.plan.io/projects/saxonmirrorhe/repository seems to be the for-real source repo
Now compare this with JSON ecosystem
Saxonica, the company behind it, has been critical for the evolution of the XML ecosystem.
I agree that lack of alternatives sucks but the breadth of options you refer to is backed by an army of open source volunteers.
When XSLT 3.0 tells a joke, it starts with "a JSON walks into a bar..."
https://github.com/Saxonica/Saxon-HE