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)
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)
Or you can just use a giant winch-operated catapult instead.
https://en.m.wikipedia.org/wiki/Leach_trench_catapult