Yes indeed - I’ve never used TMON but keep meaning to play around with it. But you can certainly do that with Macsbug on all versions of 68k Macs. Install Macsbug, press the programmer’s switch or (on some machines) Command-Power, and try the HD (heap dump), DM (display memory), or IL (instruction list, i.e. disassembler) commands depending on what you want to do.