Arduino and Raspberry Together

I have an Arduino Nano linked to a Raspberry Pi with multiple analog sensors. I use the Pi for Ethernet connectivity, data collection and for the Pi Camera to keep an eye on the sensors.

I’d love to use Cayenne as my dashboard but it seems that I need some sort of Arduino networking shield in order to “register” the device and get a token before I can connect to Cayenne using Kens method above? Is that correct?

Ethernet and Wifi on Arduino seems particularly clunky and especially with a Nano. Is there not a way to register via a PC or Pi without the Arduino needing its own Wifi or Ethernet?

Also if I added more Arduinos would they need to be individually registered?

Any help / guidance is much appreciated.

Pete