Just wondering if there would be plans in the future to get other controllers compatible with the Chromecast Ultra. I know business-wise they want to sell the controllers, but I'm wondering if it's even possible to connect any current controllers to the Chromecast Ultra in the future.
I highly doubt third party controllers will be supported on Chromecast any time soon as it would require a completely new peripheral to connect them such as some kind of wifi hub that accepts USB connections and connects the input devices to the Stadia service. I know I'd like to see a device like this so that we can connect keyboards and mice to Stadia when playing on Chromecast.
As it stands, there is no way to directly connect any controller to the Chromecast - the controllers must connect directly to Stadia via the network.
Hopefully for those of us that have Nvidia Shield TVs also Google and Nvidia will implement Stadia support via those devices. If that becomes possible, then third party controller/keyboard/mouse support on TV would become easier.
You can currently get around this by connecting a PC/Laptop to your TV (instead of Chromecast Ultra), and use nearly any input device you want.