I found the Stadia developer experience to be pretty solid. The visual studio integration was top notch and worked, with a few minor exceptions, without a hitch. Having worked with all major gaming platforms to come out in the last two decades, Stadia was certainly not the worst.
Shortly before Stadia was ramped down, there was a talk about Stadia team starting the Stadia Porting Toolkit, as they weren't getting enough studios interested in porting their XBox/Windows engines into Stadia, versus what they would get out of GeForce Now and Cloud Game Pass.
