68K apps do indeed run in Classic. Even some phenomenally ancient ones that just sort of accidentally happened to be 32-bit clean and therefore made the transition to System 7 / 32 bit environment.
In the early OSX days I had a System 4 era DISK ACCESSORY named DeskZap which was the most efficient little tool for getting low-level code info on classic documents that OS X didn’t understand how to open yet, so as to know what they were. Worked fine in Classic.