Generic Binary Sensor

I update my alarm’s motion sensors’ sate in HA with the HTTP binary senor. However, this means that when I restart HA, I can’t see all sensors until they are actually triggered.

So I’d like to add them in configuration.yaml and keep updating their state via HTTP.

What’s the best way to include them into the configuration, given that they don’t exist until triggered? With a template binary sensor?

Yeah template binary sensors would be the go.