Don't know of a shortcut to move the Flashlight to main panel. Only that
you swipe-up to gain access to the Flashlight button. The control panel for
the light for iPhone 6s in iOS10, improved. The '3D Touch Action' Menu works
flashlight button options when it is held down.
That still sounds like two things -- just to turn on a light. The touch & drag
stuff is why my iPad lives inside its box. Much of the touch requires styli.
And when the touch-keys fail, things like passwords cannot be used.
There are some apps that could be used to turn on the Flashlight; while all
appear to need you to run the iOS to access them. Without any urgency?
• Use Control Center on your iPhone, iPad, and iPod touch - Apple Support
• How to use the flashlight on your iPhone and iPod touch - Apple Support
As you've likely already exercised the methods prescribed in the above...
• Product Feedback - iPhone - Apple:
https://www.apple.com/feedback/iphone.html
...You may have to send Feedback to Apple. Suggest a shortcut button to
remove this function from the rest of the iOS. An Emergency Flashlight is
a thing that should be easy to use. ~If a vanity light, not so much urgency.
With a lock-out so the phone battery and light aren't wasted by accident.
I always carry a real flashlight of quality and long battery life, year round.
Spare flashlights can be good, especially indoors during power outage.
But do not want to launch an operating system to turn on a flashlight.
Good luck & happy trails! 🙂