FracturedJson does not add any extra data; it only changes the formatting (it is a way of automatically formatting JSON data, not a new file format). However, the documentation mentions that in some cases it does reorder or rewrite things (such as the order of keys, the number of decimal places, etc).

If you set CommentPolicy=TreatAsError then programs that convert it to a canonical form (whether or not that canonical form is JSON or some binary format intended to be like JSON) should (hopefully) result in the same output with the original and the one converted by FracturedJson, depending on what things are considered to be significant. (I tested this with a program I wrote, which converts JSON to DER (which is a canonical form (and, in my opinion, usually the only good one) of ASN.1), and does not consider the order of keys or the representation of numbers to be significant (although the conversion of numbers does not lose any precision and is converted exactly, but e.g. "1.2" is considered the same as "1.200" and "80e1" is considered the same as "800").)