I think for flares, we should go for more use.
1. First, it should exist as a standalone
Kampfpistole equivalent, with fitting flare, smoke and frag and optionally HEAT ammo (the Germans did experiment with it, and it was theroetically able to defeat 80mm of ammo, but the range was deemed to low and instead they opted to research the Panzerfausts further, and since we have an RPG since long time, it might be really uneccesary, but probably a nice thing to have as an option). Could also make use of those crazy message sending ones, spies would probably love that one.
2. Useable as either standalone tubes on planes, or in worst case,
like the
Arado 234.. If you look at the right side, you might spot an flare gun pointing outwards - a thing that actually existed on many planes, albeit usually just in form of port for the pilot own flare gun - it served as backup communication device and a way to signal own position over friendly territory. Since our jets (opening a window is less of an option for those) are fine for now, we can even get away with not making it more modern integrated flare launchers. I am a bit too busy to look for sources, but I am pretty sure most Allied bombers just shoot those out of the window, Americans particurally used the flare gun to signal which plane requires to land first due to wounded crew.
3. Useable on tanks for smoke grenades, frag grenades to clean nearby infantry (although combined with Blood Eagle could be easy suicide method) or even flares if they try to make infrared AT missiles, either as
Nahverteidigungswaffe launcher or one of the more common, simple tube launchers that were mounted on the sides of tanks.
4. Optionally, we could make it useable as standalone
Sturmpistole, which is basically Kampfpistole but with a stock, or an underbarrel launchers for our guns.