I think your boss is telling you that she herself would keep it a secret for you and not tell anyone else what your ideas were.But at the same time she is telling you not to tell others if you do decide to go ahead
She also doesn't think the higher-ups would go for it. She is evidently friendly with you. If you do decide to go above her head she is saying you may bomb out and get a reputation for pulling fast tricks on the company. I wouldn't take the chance a good reputation is hard to build and quickly torn down by one or two devious acts. I think I would rather not take a chance with being fired or being monitored by the company after that. Once two people know a secret it is in my opinion , no longer a secret Auntie