Isaac SDK 2019.3 doc has a page titled “Connecting Adafruit NeoPixels to Jetson Xavier”.
In that it points to a sample application //packages/led/apps/led:sample_led-pkg, but I cannot find it in the Isaac SDK 2019.3.
We are investigating. The documentation had been released, but the led package itself with NeoPixels support appears to not have been included in 2019.3 nor 2020.1.