It does manage the battery (if SatNav used), and will save battery usage to use in hybrid mode back home - except home is your final destination, so all the timings and mileages are to back home, not to your actual destination which is now just a waypoint.Folks driving Golf GTE report around 60/70 mpg 'real world' but its going to depend on use.
Phev are really for people like me who would spend 70% of their time on EV around town with the rest in hybrid mode. Over a year my overall average if ran one probably would be around 600 mpg because I'd be running in EV the majority of the time.
Most VAG EV (so I assume SEAT/Cupra are the same) will manage the battery if the sat nav is used