wrote:
Using a Garmin G530W, how is vertical guidance provided on LNAV/VNAV
and LNAV+V approaches?

Is it the same as LPV approaches, i.e, the GPS drives the HSI/LOC
glideslope? Or are there other means?

I can't find it documented anywhere...

It is the same WAAAS-derived vertical path but the FAA provides all the
highly accurate anchor points only for LPV IAPs, and only from the PFAF
inbound.

The FAA does provide data for VNAV/LNAV IAPs, so you don't have to worry
about stepdown fixes inside the VNAV PFAF, but the computations of the
path are not as precise as LPV. It's an unimportant distinction for a
pilot, though.

With LNAV+V it is strictly a Jeppesen add-on so you need to keep an eye
on any stepdown fixes, especially prior to the FAF. Inside the FAF the
path should be good to MDA.