Can i fake having a gyroscope?
You can, but it requires extensive android development knowledge, rooting your phone (which i do not condone and do not take responsibility for any errors that occur if you choose to do it). This isn't even simple rooting either. You'd need to know how use XPosed, and the module for it isn't even complete either. Even if you did manage to fake a gyroscope, using other sensor data, it would still come out as lackluster, and ruin your pokemon go experience. hope that helps.

sources: http://forum.xda-developers.com/android/help/app-request-gyroscope-emulator-virtual-t3186938