I've been developing on the Google cloud, but am continually evaluating AWS and Azure, both of which are bigger providers in this space (AWS being the biggest). For technical and business reasons I'm on Google even though Azure, at first glance, appears to be the better fit. So the answer is yes I know about their cloud products, but am not actively developing on them.
I develop on iOS, Android, CE (yeah, still used), Microsoft, OS X, Linux, well basically everything. Not all at once though, usually 2 or three at a time. Yes I work from low level firmware, FPGA even, all the way up to the cloud. At the moment am working in firmware, Android and Cloud actively for work.