Cool! I can see the boot process and get my root shell with the serial connection. I created the file,
iface enx8cae4cebd01b inet static
Interestingly, it didn’t seem to work. Then I tried a dhcp configuration I found on the Debian wiki,
iface enx8cae4cebd01b inet dhcp
Not sure why that didn’t work, either (found nothing, scanning my subnet) but
When I went back to the same static config I initially tried and gave it another reset, it came online! Maybe I had goofed something, but I dunno.
Anyway, thanks again!