I had already found that section on ECM and it doesn’t say anything about local vs. non-local IP address. It just describes how to enable ECM mode. Why is ECM mode behaving differently from the LE910* models? My understanding is ECM mode on LE910* will give a non-local IP address to wwan0.
Now that I have LE910C4 working with PPP and giving me a non-local IP address, I tried replacing the LE910C4 with ME910C1 and re-ran sudo ./ppp_install_standalone.sh. This time I specified ttyUSB2. The script ran without error and I rebooted the Pi. ppp0 was there with a non-local IP address, but ping thru ppp0 does not work.
So something isn’t right with the PPP instructions/scripts for ME910C1.