Is pass-thru tethering for my camera possible?

I’m interested in knowing if there are ways to effectively tee the input of a tethered camera. I want to be able to connect to a SBC (aka RaspPi) from my camera, and then to my laptop from my SBC. I want the camera to see the SBC as a USB Mass Storage Device so I can use it as a location for tethering. Then, I want the SBC to effectively send using the same approach the files sent to the connected computer. I really am not sure exactly how tethering works, since I read about Picture Transport Protocol and more recently USB Mass Storage Device protocol as the means by which cameras communicate. I’m confused. Please help.