Like Eric says, they are not interchangeable. Good to go is an idiomatic use of good. Good to go means OK to go ahead, all set to go, ready to go etc.

“Good to go” and “good to do something” actually means something slightly different than “ready to go” or “ready to do something” Ready means a person can start now. It’s about checking if someone is prepared. Good refers to whether there is agreement between you and the other person that you both are on the same page. For example, if we are going to a party and I know you are getting dressed, I will ask you if you’re ready to go. However, say we had an argument and I’m not sure if you’re still mad at me, I will ask if we’re good to go out now.