Right, but some of the old units (the 10 year old but still widely
used Garmin 195 being one case that keeps popping up anecdotally)
don't implement this properly.
I used to own a 195, and I'm pretty sure that it alerted me when it lost
position, but I no longer own it, so I can't verify if or how this
functionality existed. It's easy enough to implemented I can't imagine
any hand held manufacturer excluding it.

that's exactly why there are IFR-certified GPS's that must adhere to
some basic design, operating principles and functionability
and then there are 'other' GPS's. There
is no such thing as a 'VFR GPS.' It is just an 'other' GPS. It could
be a Garmin Forerunner to a Garmin 396. As long as it is not certified,
who knows where it falls between those. Now we all know the 396 is
on the same level as a IFR-certified GPS but all those others leave
a LOT of room for interpretation in the design none of which the user
has access to (manufacturer proprietary).

Gerald