You are writing this as if JSON was a newly invented thing, and not a language that has become the lingua franca of the Internet when it comes to encoding structured data. Well understood, and universally handled, since 1997.

A 100 digit number cannot be encoded losslessly in D-Bus btw, nor in the far majority of IPC marshallings on this word.

Having done systems-level OS development since 25y or so I never felt the burning urge to send a 100 digit number over local IPC.

Not that 100 digit numbers aren't useful, even in IPC, but typically, that's a cryptography thing, and they generally use their own serializations anyway.