Where does one even start with learning BGP? It always seemed super interesting to me, but not really something that could be dealt with on a small scale, lab type basis. Or am I wrong there?
You can simulate arbitrarily large networks and internetworks with this, provided you have the hardware to run a large enough number of virtual appliances, but they are pretty lightweight.
They've got some Docker examples in the README.
Networking talent is kind of hard to find and if you learn that your chances of employment get pretty high.