TL;DR of Scott Ritter's analysis:
https://pete843.substack.com/p/scott-ritters-take-on-hospital-bombing
TL;DR again?
PIJ rockets are made from stolen water pipes, with small payloads of under 10kg of improvised explosives. That can't do the damage observed.
But Hamas seems to be hiding something too. No weapons were found at the scene, but its likely one or more of their operatives was taken out in the hospital attack, probably someone senior.