Remote Mouse - Turn your smartphone into a wireless touchpad and keyboard now!
Monect - Make the best use of sensors on smart device to control PC, simulate steering wheel, game-pad...
KDE Connect - Integrate Android with the KDE Desktop
LEA Extended Input - iOS/Android app with windows server to control functions in games via your smartphone/tablet.
aGamepad - aGamepad allows you to use your Android based phone as gamepad for Windows.
Macro Deck - Use smartphone as macropad for pc