MPK is a C++23 library that can be used to serialize MessagePack blobs to C++ data structures. It is mostly-header but requires linking with either the static or dynamic version of a library.
It also provides a CLI tool that interprets a file as MessagePack data and outputs something akin to human-readable JSON code.
It was originally spawned from Voxel Garden.
You can find the full code in GitLab.