There was a plan in 1943 to drop Welrods into German-occupied territories for the mass assassination of Schutzstaffel (SS) and Gestapo officers and soldiers within a one-month period by resistance units. This plan was possibly delayed or called off in the aftermath of Operation Anthropoid, the assassination of Reinhard Heydrich by Czech resistance forces.[1] In the wake of his assassination, an estimated 13,000 civilians were arrested and interrogated, 5,000 civilians murdered in German reprisal killings and the villages of Lidice and Ležáky destroyed.
Commentary from someone quite trusted in the historical gun community and who’s actually shot multiple Welrods/VP9s: https://www.youtube.com/shorts/POubd0SoCQ8
It’s not a VP9. Even at the very start of the video, on the first shot before the shooter even manually cycles the gun, gas is ejected backwards out of the action rather than forward out of the suppressor.