Ok, I will read more thanks. I already found a loosely sourced article here..
I suppose I had overlooked what should have been obvious, especially since I already mentioned MPIM (Multi-Purpose Individual Munition program, a program in the 1980s looking for ways to launch munitions without backblast), but the football grenade appears to have been spawned from looking for a way for soldiers in urban areas to attack armor from inside buildings and to reduce how visible they were during attack. I’d still rather have a way to launch it though (PIAT gang 4 life).
Looks like possibly only one was made, so I guess not a super successful program, but I’m genuinely interested to see if there’s any more deep lore on it.