If you got access to both GameWorks and NvPhysX repositories and accept (and obey) boths terms, you can mix them, you just can’t publicly distribute source code from the things you combine as it would clash with the licensing terms. It’s perfectly fine to integrate GameWorks tech yourself and use it internally for your products, as long as you are fine by both licenses terms and don’t break them.
Worth noting that integrations under NvPhysX fall under UE4’s licensing terms and they differ substantially from the terms on GameWorks repo tech, so do take your time to examine the licensing differences if you go route.
All being said, unless you absolutely need to be using the latest version of some tech without ue4 integration, just don’t. Nvidia will upgrade these eventually and manually upgrading these just to try something out isn’t in general worth the effort. If the library changes are small, you can swap the lib with small effort but sometimes you need bigger changes from UE4 side (which immediately makes it slow and tedious task unless you got high-end workstation or distributed build system)