It may be propoganda
I have never seen a Nano offworld, so it may have just been Omni propoganda. We all know how accurate it can be.
There might also be a question of surviving vs thriving offworld. Perhaps there was some excursions of nanos offworld, but it may have been at great personal discomfort even damage to themselves.
Personally I could not imagine a nano without the ability to control its bots to perform its basic hygene and make coffee in the morning. Its kind a funny image, Mr Big Brain cant figure out how to use the shower....
Ani.