Looking at the cartridge in the lead photo, I can tell you that it wouldn't have worked with the US version of the NES. It's only about half the size of the grey brick cartridges sold in the US, and that means that the modem port won't be accessible. Also, the demo video shows that the Google Maps cartridge can make use of the microphone found on the original controllers. Trust me, those really were made, they just weren't included in the US version of the NES.
And if you don't have an NES console but would like to try out the new 8-bit mode, head on over to Google Maps and click on the Quest button.