We use JSON5 for two reasons:

1. Comments 2. Trailing commas

We don't use any other JSON5 features, which are primarily just that numbers may be encoded in hexadecimal and field names may have quotes elided.

We typically encode values with RFC 4648 base 64 URI canonical with padding truncated (b64ut) with values too large to be a JSON number, so hex isn't useful anyway. We haven't found that omitting field name quotes is a big deal.