the greifelt drilling have this lever on the left side and a slide on the stock wrist.

because a common drilling have the greener safety where the lever is one can assume that this lever is also the safety and the slide on the wrist activate the rifle barrel.
but thinking that the drilling hanging on your back, maybe together with a rucksack, the chance is very high that some movement disengage the safety unlike the greener safety where is some protection.
till someone know it better I can only believe that the lever activate the rifle barrel.

nitrox, I hear that you would like to have a waldläufer!
its not recommanded to shoot game bigger like rabbits or birds and not on more that 50-80 meter with a 22 lr.
I had never a waldläufer in my hands but think that accuracy will be good enough for such hunting situations. of course, its not a target rifle!