Kali Linux Building GNURadio from Source to Possibly Enhance Performance

This is where I keep notes to remind me of what I am doing, because I tend to rush through solutions and forget what I did just 2 minutes ago,

Turns out that pybind may be important later on when studying GSM signals.
Found out that I cannot simply do a "pip install pybind11", because only C header files are downloaded with no cmake configuration.
So build from source:
git clone https://github.com/pybind/pybind11
cd pybind11
mkdir build
cd build
cmake ..
sudo make install
Somewhere in the above process I got an error on pytest.
So, pip3 install pytest
Then, export PATH=$PATH:/home/mya55/.local/bin , which happens to be where pytest landed.
Then, continue with cmake .. , sudo make install. (SUDO because may not have write access on target directories.)
Now follow instructions starting at the section Installing Volk. https://wiki.gnuradio.org/index.php/InstallingGR#Step_2:_Installing_Volk

During make, got "cannot find -lgsl::gsl", so
sudo apt-get install libgsl-dev.
Then start over with
sudo cmake -DCMAKE_BUILD_TYPE=Release -DPYTHON_EXECUTABLE=/usr/bin/python3 ../

Now what's messed up is that I also ran
sudo apt-get install gnuradio
to see what would happen.
Now there is a /bin/gnuradio-companion and
/usr/bin/gnuradio-companion and
/usr/local/bin/gnuradio-companion
The shell execution path is /usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games
For now, I will leave things alone, because simply typing "gnuradio-companion" on the first shell prompt works.
Now I will test the HackRF One's ability to detect GSM signals coming from my own phone. See https://osmocom.org/projects/gr-gsm/wiki/Installation