Rewire the power button so it's an easy to push switch and put it behind a target. Then your remote can be a nerf gun. Edit - the other thing that came to mind

Rewire the power button so it's an easy to push switch and put it behind a target. Then your remote can be a nerf gun. Edit - the other thing that came to mind was to look into HDMI cec and see if there's a setup where turning on your tv will turn on the PC automatically. Edit 2 - if you go with an app, you could use something like tasker and then you can have different triggers like your phone tapping an nfc sticker (then you don't have to unlock and find an app).