Does an "IFR approved" GPS placard require database updates?

Exactly... Using it for an IFR GPS is all about the POH supplement.
Garmin requires updates. UPSAT did not - just required that you verify
that the approach hasn't changed.

None of this prevents you from using the GPS, of course, for enroute
VFR use.

Now some years ago there was a controversy started by Flying magazine
because of the speculation that an over zealous FAA inspector might
view an out of date database as a violation. But the FAA clarified
that this was not the case. Same deal as with outdated charts in the
plane. Perfectly okay... But you MUST have the current information
you need to complete the flight safely. That same outdated chart (or
database) won't get you out of jail if you violate some airspace (or
worse, violate the terrain).