"Any JSON primitive" does add a few requirements not semantically comparable to CSV, like numbers that are numbers, and keywords true, false, none.

When these syntaxes are parsed into objects, either the type info has to be retaind, or some kind of attribute tag, so they can be output back to the same form.

> make it so any consumer can parse it by splitting on newline and then ...

There is something like that called JSON-lines. It has a .org domain 'n' everything:

https://jsonlines.org/