A common thing in JSON/YAML alternatives is to support more types through syntax. I don't think this is a good idea. YAML already did this badly with the Norway problem, but JSON also has issues with eg "is it float or int", what about nulls, what about precision... and so on.

There are many, many more types to support and all this does is complicate syntax; the types can be relegated to a schema. For example, where are dates, with or without timezones, what about durations, what about SI units for mass, current, what about currency, what about the positive integers only, numbers as hex, as octal, as base64...

One format that _nearly_ gets it is NestedText https://nestedtext.org/en/latest/basic_syntax.html ... which means everything gets ingested as strings, dicts or lists, which vastly simplifies things; my quibbles with it would be it still went for multiple syntaxes (for dictionaries, multiline strings, inline vs multiline dicts&lists. And yet, it still didn't make comments part of the data model (which is so useful when processing or refactoring files). While it's not perfect, it does separate the validation of scalars, not stuffing someone's priority list of validations into incomprehensible syntax.

YAML's been a decades long mistake and making JSON more like YAML is not the way to fix that.