You can use this: "On any touch" and enable an entirely event sheet after this, and doing your sprites to appear on this code (setting them invisible doesn't mean they will be untouchable, so, only create then when any touch is detected is a better way to go..)
There is somewhere an option called "touch screen is detected", or "on touch enable", I remember this option but was unable to find it.
What you described works, but it's a hack. Suppose the user is on Android, which is on phones with a keyboard, but that user touches the screen. Given that Android devices vary in screen size, I would prefer the user play with the keyboard instead of using touchscreen controls, which would take up 1/4 of that player's screen at the least.