Comment by MountDoom
But why? You can have the same chip for much less. The "toolchain" is just a bit of syntactic sugar around existing languages and tools, but more to the point, nothing stops you from using it with your own hardware.
I'm not doubting you, just sincerely curious.
If they've done 500k units, "based on a respun Uno" almost certainly means "there's a atmega328p on the PCB, a 16MHz crystal, and some points granting access to the serial and reset pins"