Yeah I had the same issue with RPi 3 and RPi 4 as shown here: Cannot push to Balena device that appears to be functional: Supervisor API ECONNREFUSED - #35 by klutchell
Normally this did not work until one reboot, then it worked. @klutchell - seems like you can open up the bug again and it should be wider now with Jetson Nano, RPi 3 and RPi 4 this time.