From what I've been told it wasn't uncommon to find a dead German lying alongisde a road, his high quality Mauser or Luger and ammo gone, and a discarded Liberator lying beside him. (In case anyone thinks a cheap handgun is worhtless against an army)
Most built were never used. The real intent was for their use in the Phillipines and in China, against the Japanese. In Europe, in those situations where there were trusted resistance cells, it was more practical to airdrop explosives and radios for the most part, as their intelligence value was greater than the lives of a few thousand stray German guards. But killing those guards requires that the forces so employed be doubled so they can look out for each other.
And at that point, the American carbines and British Sten Guns provided to such groups sometimes came into play, if only to keep the Germans from becoming complacent.
Something similar was built for the Vietnamese during the 1960s. Problem was, the South Vietnamese were afraid the Montagnards would use the little *deer gun* pistols against them as well.
