Status: evaluating options...
Still not sure if USB, Wifi AND Bluetooth are required. Would also be nice to add a microSD card for logging, although the computer could do that (might not always be connected).
For USB-CDC and Bluetooth SPP: use LAWICEL protocol.
Other option would be to use ESP32; it has CAN, USB to Serial, Wifi and BT.
For USB: would be useful to act as device, and charge the SmartPhone / Tablet in the process... Charging Android phone while it is in USB Host mode: possible with resistor on micro USB type B ID pin.