> > I'm not sure what protocol would be running over the USB2 interface - maybe > PPTP - equivalent to some of the dial-up protocols. >
A small note: PPTP works on top of IP, it is a VPN protocol. It encapsulates PPP protocol (which I believe you were talking about). PPP can run IP over point-to-point connections like VPNs or serial/com ports (connected either directly or with dial up modems). There are alot of serial ports for USB and Linux supports them: https://www.kernel.org/doc/html/latest/usb/usb-serial.html So, it should be possible to run PPP-over-usb with a usb serial converter. There are ethernet adapters for USB, but not of all of them are supported by Linux https://www.amazon.com/AmazonBasics-USB-Ethernet-Network-Adapter/dp/B00M77HLII
