mentions some good ideas, some of which can be very easily implemented due to Steam client framework supporting things like
There are also control pad apps for phones,which still stink because you are still using the phone as a touch controller. Not saying anything about your efforts. It’s just a limit of the devices in question. 2 best options for me that work are PS4 controller wired(works 100% with no additional config) or Steam controller over virtualhere, which works great with the only rub being Android devices MUST support USB host mode.