Greg Esres wrote:

You will note the warning message Garmin provides when you pull up
and ILS approach.

Yes, and I consider it to contradict what the manual says. The note
says for "monitoring" only, insinuating that approach guidance needs
to come from the underlying navaid at all times.

That's part of the reason I asked the question. I have difficulty
explaining away the inconsistency between the note and the
permissiveness of the manual.

You should discuss that with Garmin. The restriction is meant to apply
to the final approach segment only. It doesn't bother me because I know
it's the same for FMS/LNAV in a 777 or a Garmin 430 in a Cessna 182.
You are using terminal mode except for the final approach segment.