

As a homelabber and systems admin, I would start with learning how to use Linux on the command line.
It’s all well and good looking at docker, but if you don’t know how to move about or edit on the command line. Your going to get stuck real quick.
Once your happy doing simple tasks on the command line, I would actually look at running something like wordpress on a pi or VPS. That will help you understand how to connect services together, and cement your basic command line knowledge.
Not sure about linking 2 HAs together, that could get complicated real quick.
If you have your DMZ setup, put HA in that and only allow web access from your main network. Also with camera, there is a feature to allow direct access if you and the camera are on the same network.