Tried to play on Chrome With my Samsung Galaxy tab s6. Samsung dex enables and chrome Desktop option activated.
I have a mouse not detected error when I start a game
Mouse is bluethoot.
The Keyboard work just fine.
I suppose that is on Stadia's side. I tried to use my Galaxy Tab S6 keyboard (with mouse), Bluetooth mouse, wired mouse thought USB-C adapter.
The Bluetooth keyboard and wired keyboard worked with the same configuration with Stadia.
Mouses worked with others app.
So we have to be patient. I hope that the Stadia app will work soon on Galaxy Tab S6 tablet
Same issue here with a S20. It seems like the Stadia website is not able to handle mouse and keyboard with Chrome in desktop mode on Android.
Hope this will be fixed in near future.