Error with pip install -r requirements.txt

I am trying to install ckanext-spatial on a ckan 2.10, python 3.9 on a devian 11 SO. The first problem I found was when I try to install the packages is that package libgeos-c1 in debian 11 is now libgeos-c1v5, also my so selects python-dev-is-python2 instead python-dev (This I don´t know if I may force choosing python3-dev). Once I've corrected this two issues it aparents to install fine the python packages and the ckanext-spatial plugin.

The problems comes when I try to install the requirenments with pip install -r requirements.txt. Then it gives me the next error: proj executable not found. Please set the PROJ_DIR variable. I've tried to install pyproj in my /lib/ckan/default/lib/python3.9/site-packages and put the envioronment variables to:

export PROJ_DIR=/lib/ckan/default/lib/python3.9/site-packages/pyproj

export PROJ_LIBDIR=/lib/ckan/default/lib/python3.9/site-packages/pyproj.libs

export PROJ_INCDIR=/lib/ckan/default/lib/python3.9/site-packages/pyproj/proj_dir

but still gives me this error: FileNotFoundError: [Errno 2] No such file or directory: '/lib/ckan/default/lib/python3.9/site-packages/pyproj/bin/proj'

Reproduce the failure from requirements.txt on Debian 11 with CKAN 2.10 and Python 3.9, focusing on the missing proj executable and the reported pyproj paths. Check how the installation uses PROJ_DIR, PROJ_LIBDIR, and PROJ_INCDIR; done means pip install -r requirements.txt completes successfully in the stated environment.

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