Remote Mouse - Turn your smartphone into a wireless touchpad and keyboard now!
EarTrumpet - Volume Control for Windows
KDE Connect - Integrate Android with the KDE Desktop
Volume2 - Volume2 is an advanced Windows audio mixer, a complete replacement for the standard Volume Control.
Monect - Make the best use of sensors on smart device to control PC, simulate steering wheel, game-pad...
Sound Control - App-specific volume control