I was able to find some photos of the MAX and NG stab trim cutout switches on Jon Ostrowers old flightblogger photoreel:
737 MAX:
737 NG:
It appears that the two trim systems which were labeled "Main Elect" and "Autopilot" on the NG are now labeled "Pri" and "B/U" on the Max. One would ASSume that this means Primary and Backup. It would be useful to know if there are any operational changes to the system besides the labels. It is unlikely that they would have made have made a change to the labels without a reason.