How do I build PKGCONF and LIBFFI and subsequently Python3.9 with ctypes support without sudo and write access to /usr/local?

How do I properly configure pkgconf and libffi to allow the python3 build process to correctly use my libffi version at every step of the build process, in order to import the _ctypes module correctly? Which piece am I missing here? #### Some background I am trying to build Python3 from source to build a GUI with PyQt5, and one of the requirements is a functional libffi-dev library. I don't have sudo permission on this SLES11 machine or write access to the typical library directory, nor are those likely to be granted. I reached out to the team who manages the machines, but they were unwilling to update the whole system set of libraries for my project. I have to resort to building ~30 dependencies from source, and I have little experience in this, but I'm familiar with the configure-->make-->install process. I'm stuck on one final piece of the process (failure to import the _ctypes module), which can be traced back to a missing symbol from the FFI library. *** WARNING: renaming "_ctypes" since importing it failed: build/lib.linux-x86_64-3.9/_ctypes.cpython-39-x86_64-linux-gnu.so: undefined symbol: ffi_prep_cif The libffi library built and installed without any issues, and I can see the files in the local library path, so I have reached the conclusion that there is either a mismatch between the libffi version and another dependency, or pkgconf is unable to locate the library. Based on my observations of the behavior of pkgconf when isolated and instructed to validate the libffi.so file, it is most likely the latter. But, I am virtually a complete novice with this, I've been at this whole build for about a week now, and I'm here typing this question, so I'm clearly open to hearing some other ideas! **Some useful debug**

pkgconf --version 1.7.3 https://distfiles.dereferenced.org/pkgconf/pkgconf-1.7.3.tar.gz 
libffi 3.3 ftp://sourceware.org/pub/libffi/libffi-3.3.tar.gz
Python 3.9.1 https://www.python.org/ftp/python/3.9.1/Python-3.9.1.tgz 

I provided the options to specify a local library directory while making the pkgconf source

./configure --prefix=$HOME/LIBRARIES/--with-system-libdir=$HOME/LIBRARIES/lib:$HOME/LIBRARIES/lib64:/usr/lib:/lib --with-system-includedir=$HOME/LIBRARIES/include:/usr/include

My PKG_CONFIG, PKG_CONFIG_PATH, LD_LIBRARY_PATH, LDFLAGS, and PATH are updated to reflect where the libffi pc files and pkgconf files are located

$ echo $PKG_CONFIG
$HOME/LIBRARIES/bin/pkgconf
$ echo $PKG_CONFIG_PATH
$HOME/LIBRARIES/lib/pkgconfig:$HOME/LIBRARIES/lib64/pkgconfig
$ echo $LD_LIBRARY_PATH
$HOME/LIBRARIES/lib:$HOME/LIBRARIES/lib64
$ echo $LDFLAGS
-L$HOME/LIBRARIES/lib64/ -L$HOME/LIBRARIES/lib
$ echo $PATH
$HOME//LIBRARIES/bin:/usr/local/bin:/usr/bin
$ ls $HOME/LIBRARIES/lib64/libff*
libffi.a libffi.la libffi.so libffi.so.7 libffi.so.7.1.0

**AND YET** pkgconf --validate validation of the library appears to fail, and the Python3 make script notes the undefined symbol. I'm more concerned about the make script; I'm not sure whether pkgconf is actually supposed to error out here. *Update here:* the library is valid according to pkgconf, so this rules out that suspicion. Thank you, telcoM

pkgconf --validate libffi 
$HOME/LIBRARIES/lib/pkgconfig/libffi.pc:9

Adding the configure command for Python3 for clarity

./configure --prefix=$HOME/LIBRARIES --enable-shared --with-system-ffi=$HOME/LIBRARIES/lib