How can I let top show in byte for memory usage on MacOS?
Any command you enter in Terminal.app provides help with the "man" command. For a list of the options on "top" you would type in:

man top


I had a quick look through the options and I did not see anything that allowed you to change the displayed memory units. Perhaps if you had a closer look?

Wondering if there is a way to feed the output through something else that would convert to bytes. Possible but that is beyond my meagre CLI skills...