Use with pybind11 to package external dependencies in the wheel?

So, if this is the wrong place to ask this question you can bump me elsewhere (I just wasn't sure what that elsewhere was). I'm trying to understand how to create a self contained wheel for a private package I'm making. It depends on a 3rd party library for which I have headers and a .so file (but no source). I'm wrapping the libray with pybind11 and so long as the library is installed such that the .so file is in /usr/lib everything goes hunky dory. However I am having the roughest of times figuring out how to include that .so in the package itself.

Milksnake kinda seems like it can help with this but I'm unsure where to start. Am I barking up the wrong tree or have I come to the right place.