That is how you use it. The battery pack has a default input and output, normally both are cigarette lighter connections.
What you do is to replace the output (female cigarette lighter) with a custom hardwire splice kit that connects directly to the dash cam.
In the case of the VIOFO it is a 5V USB-C connection. With other cams it is a 12V brand-specific plug.
But when you have a battery extender, you will never use a dash cam hardwire kit. Those are only used when there is no battery extender.
Not everyone wants to spend another $400 to get a dash cam that runs for a week without stressing the cars batteries but to me it makes the most sense as EV’s still rely on a good old 12V battery to get the car started.
Sorry for the long answer to a short question