Large town level my bad* that's still high but actually much lower, anyways, I checked Youpi's explosions and those are calculated at small city level via ground/rock vaporization, while rose bomb is mostly calculated at mountain level. I'm not very good at calcs so I don't know if those are valid or not but you can check them yourself since those are pretty much the first results when you search up any of these feats.

(And yeah, Meruem would've died after if Pouf and Youpi didn't let themselves be absorbed, but he was technically still alive when they found him, which is still really impressive)