A geli device's physical path should be the underlying provider's with "/eli" appended, if the underlying provider has a non-null physical path itself.
A commit references this bug:
Date: Wed Feb 14 20:15:33 UTC 2018
New revision: 329273
geli: append "/eli" to the underlying provider's physical path
If the underlying provider's physical path is null, then the geli device's
physical path will be, too. Otherwise, it will append "/eli". This will make
geli work better with zfsd(8).
MFC after: 3 weeks
Differential Revision: https://reviews.freebsd.org/D13979