AC 20-138C
Lot of reading..but...basic TSO146c class Delta euipment with Barro and you are well on your way in the US to LPV approaches
A telling quote
Although GPS/SBAS does not have an equipment limitation for other navigation systems onboard the aircraft, the receiver manufacturer’s operating instructions should encourage operators to retain back-up navigation systems to guard against outages or interference events.
5Hz update rate...
To date there are 100 LPV and 55 LP published approaches in the US. Considering the FAA's business model calls for 8300 LP/LPV approaches, lots of work ahead!