macOS apps which are with one button

I'm trying to create a keyboard shortcut with the MacOSwitcher app with one button.

So at the moment macOS has its standard app switcher, which is command plus tab. And that allows you to tab through each app icon and then select the app by releasing the button.

What I'd like to be able to do is, and I'm not sure if this is possible, I'd like to assign one function button so that when you tap it really quick, it brings up the app switcher, and then if you stop tapping after a second, for example, it selects that app.

Does anybody know how this would be possible?

I've made a little video of the App Switcher I'm talking about in case there's any confusion.

So basically:
tap F8 many times to go to the next app. Stop tapping to select that app.

If this isn't possible is there a way to get F8 to just cycle through all open apps (not all open windows) I can't see a way to do that.

Cheers! I love BTT, just having difficulty with is.