OSX Catalina - GCC/PIP compilation issue

I'm trying to install a tool on my computer via pip on my Mac and have been having issues.

I've seen suggestions on StackOveflow to install the Command Line Tools, to run variants of xcode-select --install, and export CPATH and CPATH. This resolved the header error. I'm now getting the error

ld: library not found for -lSystemcollect2: error: ld returned 1 exit status

and

    psutil/_psutil_osx.c:36:43: fatal error: CoreFoundation/CoreFoundation.h: No such file or directory     #include <CoreFoundation/CoreFoundation.h>                                               ^    compilation terminated.    error: command 'gcc' failed with exit status 1

Has anyone come across anything similar?