On Debian 11:
sudo apt install libgpiod-dev libcurl4-openssl-dev
Need to manually install paho libraries. I'll eventually add these to my apt repo.
Currently, these are installed system wide.
sudo pip3 install vcstool
vcs import < paho.repos
cd paho/paho.mqqt.c
make
sudo make install
cd ../paho.mqqt.cpp
mkdir build
cd build
cmake ..
make
sudo make install
sudo ldconfig