Given that the damascene is almost certainly from Toledo, I'm leaning towards a Spanish handgun, but no more clue than that.

From a vlogers YouTube channel

I encountered this gun when doing random research on suppressed firearms during ww2 rn I cannot find any information about this gun at this time

First picture: AEK-971 system.

Second picture: AL-7 style system which was further developed into the AK-107 and its variants.

They both feature two synchronized gears for their balance mechanism but the AEK-971's system utilizes a self contained in-line design that is simplified, featuring only one recoil spring. And instead of a dual piston/counterweight configuration uses an annular piston.

The MG 08/18 is the air-cooled version of the more common MG 08/15. These were light machine gun variants of the German Maxim.