I've only ever done this with my own signature (so, a one-time process), of which I have a scan and my workflow hasn't changed for 20 years, just the tools. as the other reply said, just inserting an image into a PDF is not a problem, and I still don't understand the use case of the camera. But in this case maybe I've had my signature available for longer than phones with cameras exist contributes to the fact?

I'm not saying you're wrong, but maybe all the office work I've done in my life is simply different.