I checked my receipts (email, easy to find). I purchased the ShieldTV in December of 2016. So just over 3 years ago. GeForce Now launched in October of 2015, but maybe just for Shield TV owners? Apparently they did a relaunch in 2020... not sure what that means. Better I guess?
You're both right, kinda. Geforce Now was in a ..closed-ish beta (you could get in, but they made it seem exclusive) for years. I honestly don't remember if it was called that when it launched. The polished product is what recently 'launched', and configuration is super simple. In fact, it was the xbox controller's instructions I had to turn to to figure out how to put it in bluetooth detection mode.
GeForce Now works fine with Xbox controllers with no configuration needed. IIRC it also requires no configuration to work with Shield TV's controller.