It depends on the SAP application if you can even monitor it with appmon. You might have some luck with Netweaver: https://community.dynatrace.com/community/display/DOCDT65/SAP+Netweaver
But other parts use ABAP, or have a wily agent already injected for the SAP Solution Manager.
We have run a PoC with UEM for SAP, but we mostly use DCRUM for SAP applications.
Yes the PoC was successful. The monitoring isn't as advanced as a full appmon setup of course, but it is significantly better then nothing. So if other tools aren't an option I would definitively take a look at UEM only instrumentation, to get a grasp of user experience.