There are a lot of proponents that some or all of the "JSON5" [1] improvements should be standardized by ECMA as well. Especially because there is a mish-mash of support for such things in some but not all parsers. (Writers are a different matter.) Primarily comments and trailing commas, are huge wish list items and the biggest reasons for all of the other "many" variant parsers (JSONC, etc).

[1] https://json5.org/