is there a list of UAVCAN Devices we can use with ArduPilot and how many
like GPS baro leds compass
Check here!
Proficnc Here2, Zubax, CUAV GPS have UAVCAN support. You can always use UC4H to use available peripherals on CAN. I’m running UC4H on here1 and it works good.
take a look at this here as well, have used a few of these can nodes and they are quite handy and nice especially to get older gps/compass, rangefinders working on can bus!!