I believe @busdriver may have overlooked something. Your TSO 145 or 146 avionics will "fail down" from LPV (a more constrained lateral and lower minima approach) to LNAV/VNAV (wider horizontal guidance through final - higher vertical minima) if WAAS accuracy is degraded, so yes, you can fly LNAV/VNAV to a DA with an SBAS GPS even if not baro-aided.
Your box will always choose the "best" approach available - i.e., the one with the lowest minima. If there's an LPV approach available and the signal is good, you'll be offered that by your box. If there's only an LNAV/VNAV approach for the airport or your box or the WAAS signal is degraded, you'll be served up an LNAV/VNAV, or if the signal/box has major problems, just an LNAV approach.
In the AIM 1-2-2 b(1)(a)(1) it states:
LNAV/VNAV incorporates LNAV lateral with vertical path guidance for systems and operators capable of either barometric or SBAS vertical.
See boldmethod.com for a great comparison of the RNAV GPS approaches.
As GPS is more reliable (if the system is up...) than temperature sensitive baro-aiding, that does make sense.
What I'm not clear on is if the LNAV/VNAV step down fix altitudes need to be honored even if flying the glideslope with WAAS. One's avionics manual may dictate that - I haven't dug through mine to find out. It seems like an overabundance of caution and a relic of when these were flown only baro-aided, but something I'd be willing to do for safety sake. If anyone has a quotable source for an FAA opinion on that, I'd be grateful.