Based on that, I believe Giles is mistaken in the Eurogamer interview cited by Wikipedia. The demo was on Gameboy, not NES. The also-linked NintendoLife article also mentions the demo was on the Gameboy. But I guess maybe that's actually more impressive!
https://gamehistory.org/eclipse-the-demo-that-sold-3d-to-nin...
Based on that, I believe Giles is mistaken in the Eurogamer interview cited by Wikipedia. The demo was on Gameboy, not NES. The also-linked NintendoLife article also mentions the demo was on the Gameboy. But I guess maybe that's actually more impressive!