Why didn’t Microsoft add vibrating to their Xbox controller on xCloud android?

Umm because the android driver is a generic controller driver not written by MS or any other manufacture

I like the idea of supporting Keyboard and Mouse for the android OS. Have you tried using a controller? I have found that most games work great with the controller on android/Xcloud.

Microsoft is getting back into the smartphone market, but with Android as its OS instead of a slimmed-down version of Windows. That probably is a significant reason why Android is getting the XCloud beta first, but Microsoft isn't foolish enough to ignore
iOS. I will be curious to play this on my iPad or iPhone.

Looks like its just for android phones and tablets and you need a controller (though i can confirm that xcloud works with nonxbox controllers).

I see, don't know exactly what might have been causing this delay on the series X controller on the Xcloud. By any chance, have you tried the Xcloud on a Windows PC or android device, using your controller, just as a test?