My guess: It’s not a crack in either the block (it’s definitely not a cracked block) or the head.
A crack in the head can lead to loss of compression and eventual coolant loss but a crack is something that slowly develops bit by bit.
It typically doesn’t manifest as a sudden engine malfunction with violent shaking.
Also a crack in the head (if one were to develop) would usually be located in one combustion chamber - definitely not spanning two.
I can say from experience, that if one cylinder has zero compression, either from a warped burned exhaust valve or a big ass crack, you wouldn’t even know it when driving. Engine power feels almost the same and the engine still runs smooth (but doesn’t idle quite as smooth- but still idles fine.
A breeched head gasket on the other hand is going to connect two cylinders together at the break, and that is too much for the engine to handle. In that case, you’d get the symptoms described: major loss of power and poor running, along with a lot of coolant possibly getting into the exhaust pipe - making a big cloud of steam out the back.
My guess: Head gasket failure
(Of course I could be wrong about that, but that’s my guess)