Remote Mouse - Turn your smartphone into a wireless touchpad and keyboard now!
Macro Deck - Use smartphone as macropad for pc
KDE Connect - Integrate Android with the KDE Desktop
TouchPortal - Touch Portal is a companion app to control a PC or a Mac by using a deck of buttons to improve the workflow & productivity of game streamers, content creators and professionals.
AirDroid - Access Android phone/tablet from computer remotely and securely. Manage SMS, files, photos and videos, WhatsApp, Line, WeChat and more on computer.
Deckboard - Deckboard helps you create macros for Windows PC and launch them on your phone.