Most exotic plausible World War 2 standard-issue weapons?

[M79]

*Semiautomatic rifles based on Fusil Automatique of 1918 or numerous others
*Assault Rifles based on various prototypes
*Earlier transistor development (1927, one Soviet and one Austrian developer, perhaps more) permit WWII electronics to look more like 1960 than 1940 with much better computers as well
*Far better RADAR equipment via further development of Cavity Magnetron in Germany (1935) and Japan (1939) - both meteorology and aircraft detection benefit
*Type XXIX Uboats or similar if Germany pushes Uboats farther than OTL between wars (late WWI Type UCIII [and UG] => Type VII Uboat; maybe focus more on U-cruisers or modular production), ideally writing off the Walther engine altogether
*Better nightvision systems via more funding to Allgemeine Elektricitäts-Gesellschaft (AEG) after developing the technology in 1935
*Reich Research Council actually does its job synchronizing and coordinating research across Germany
*Crossbows for SOE and SAS (and Axis equivalents?)
*Build the Habbakuk or GE's Walking Truck
*More production of the German plastic explosive so stable it could be milled into solid shapes like ceramic mugs or even crude silverware...

 

[Canuck Wingnut]

Have we considered the Australian effort to mount a Hedgehog anti-submarine mortar onto a Matilda II tank yet?
If that had been tried early rather than late in the war it might well have seen service as a dramatic obstacle-clearing weapon.