TIL that Ubuntu cannot be installed from packages on Raspberry Pi Zero v1, but on v2 can. But Raspbian could be installed on both. That works for me.

Played with GPIO on Jetson. I could blink with LED connected to GPIO (plus of LED connected to GPIO, minus over resistor 330 Ohm - to ground). But reading button state didn’t work for me (one pin of button is connected to GPIO, another over same resistor - to 3.3V pin).