you need to install pyserial
with pip
What’s that
a python libary.
run pip install -r pyserial
I was able to install pyserial (and yes, that resolved my initial issue). Nevertheless, the Linux instructions will not work on MacOS because there is nothing like /dev/tty.usbmodem14200
on MacOS. From what I have been able to ascertain, this is a difference between Linux and BSD.
Okay! This was successful on my Raspberry Pi:
Download neutron.img and autobooter.py
sudo apt-get install -y android-tools-adb android-tools-fastboot
sudo python3 autobooter.py
fastboot flashing unlock
And so on with the rest of the instructions from neutronscott.
So now I have Magisk on my phone. Not sure what the next step is.
Update Magisk. There is a apk that will allow USB debugging called Adbio. Look on this site for it.
Found it. Thanks. Success!!