I read stories about how people’s head literally exploded due to the to the eruption.
Yes, and it was centuries before the invention of aspirin, so, imagine their discomfort. :^)
The number of known human remains from the 79 AD eruption rose a bit a few decades ago when the former dockside area of Herculaneum was excavated, revealing dozens of huddled skeletal remains. They'd died from the temp spike or even before, from poisonous gases, then the incoming hot material caused, well, as you said.