I'm currently using pure data on windows10 and want to use an external [pix_freenect] object.
It says it has been tested and compiled for windows7, but I can't find the .dll file. How can I use it?

did you consider using pix_openni ? (puredata 32 bits only)

https://github.com/kronihias/pix_openni
with updated openni / nite installation instructions here :
https://fivedots.coe.psu.ac.th/~ad/kinect/installation.html