I finished my project using Ubuntu, and went to recycle one of those 32Gb USB stick for playing music in my car. The 2011 Honda Accord and 2014 Honda Odyssey both said nope "device incompatible" or "device unreadable" or something similar. Reformatting didn't help.
I discovered that the live-USB stick formatting program I used had increased the default offset of the partition from 1K to 4K, I think. I actually had to use "diskpart" to delete the partition and create a new one to reset the offset to the default value. I didn't see how to do that in Disk Manager's GUI.
Now I have my 32 Gb of music.