If your car has OBDII socket then there is a pair of pins with permanent battery connection, via the 15A Room fuse. However if you pop that fuse not much will work!
I tried this with my Mazda3 during lockdown, but alas a panel inside the car was next to useless here in UK with short winter day and then too much pollen etc on the screen at this time of year, all conspiring to defeat the three different panels.