Are you saying Nano is based on Ethereum? Because it's not. Or if you mean the environmental impact claims are based on Ethereum... that's sort of true (Bitcoin is still the biggest offender here, but Ethereum currently also has a significant impact).
However, Ethereum is moving to proof-of-stake, so this won't be relevant once that transition is complete.
However, Ethereum is moving to proof-of-stake, so this won't be relevant once that transition is complete.