closing as it seems to of been resolved.

It is out of scope, but can still be done in pretty much any project, using a shadow of https://github.com/falkreon/Jankson

You need to add id 'com.github.johnrengelman.shadow' version '7.0.0' to your plugins {} block, then shadow("blue.endless:jankson:1.2.1") to your dependencies {} block.

This library supports features of JSON, HJSON, and JSON5.

this is probably out of scope of fabric api