the device you're thinking about is called rifle grenade (soldiers already carry rifles with them)
sometimes 40mm UBGL fills the same role. grenade throwing device like this would probably require different fuzes (longer delay) and it will be much less controllable than anything actually launched (you don't want live grenades ending up nearby by accident, not an option with rifle grenades or 40mms)
the entire idea kinda died off because you can't fit in rifle grenade anything actually useful against tanks for example, but one resurgence would be 82mm mortars attached to PG-7 series rocket engine and launched from RPG-7, used by Ukrainians
I'm actually surprised now that I'm thinking about it that there aren't grenade flinging devices like this.
the device you're thinking about is called rifle grenade (soldiers already carry rifles with them)
sometimes 40mm UBGL fills the same role. grenade throwing device like this would probably require different fuzes (longer delay) and it will be much less controllable than anything actually launched (you don't want live grenades ending up nearby by accident, not an option with rifle grenades or 40mms)
the entire idea kinda died off because you can't fit in rifle grenade anything actually useful against tanks for example, but one resurgence would be 82mm mortars attached to PG-7 series rocket engine and launched from RPG-7, used by Ukrainians
Or you can just use a giant winch-operated catapult instead.
https://en.m.wikipedia.org/wiki/Leach_trench_catapult