So there wasn’t actually a problem, at least not once I attached a serial console. The KDE auto-mount for new device didn’t pop-up saying there was something after I ran the radxa-zero-erase-emmc.bin, and the spinner was going. It did attach as USB Mass Storage, and saw that in dmesg/syslog, but I wasn’t looking there. Once I realized that, the dd to flash the OS image was just fine.
However, from there, turns out needed to do a bit extra for uboot, as Trying to figure out whats wrong with my radxa zero describes. Hopefully that fix will be pushed into the main boot .bin and such soon, but for now it’s needed on the Zero.