The FME Python environment is a bit weird, to say the least, which makes it difficult to use in various contexts. It's a Windows Python embedded installation, with the bundled and user-installed libraries in non-standard paths. As stated by the Python doc linked above, this installation doesn't officially support using Pip for package installation (due to the sysconfig paths likely being invalid). For dependency management, I would honestly much prefer using a virtual environment, but the python311 installation bundled with FME 2023 doesn't include the venv module, so that's not even an option.
At that point, I would rather just create a separate, regular python installation, manage the packages myself and tell FME to use that instead of the included one, but then I would need to move all the compiled FME libraries (and the DLLs they depend on)to that environment, and I don't see a list of that anywhere. Is there any version of the FME Python libs that can be installed to a fresh Python environment, or are the only ones supported the ones bundled with FME, to be used by path injection around a separate Python environment like ArcGIS?