Launch any custom app (for instance, the camera!) from Locus

When I'm hiking or biking I use the phone only with two apps. Locus, and the Camera.

Switching

between the two is quite unconfortable especially because I use Locus

full-screen (so to take advantage of all the available size of the

screen). So to move to the camera I have to swipe a border of the screen

to get to the home page, from which I can launch the camera.

What about a custom button to launch any app I'd want to? I found how to launch some "co-apps" but not any app as I may want to pick directly from Locus.

Thanks!