The purple wire appears to go to a 5A (FS4) fuse in the passenger fuse box, then it changes to blue and goes on to a junction box above the battery to a 20A fuse (FE41). There are various connectors. At which point does the 12V drop to 7.7, is the thing I’m interested in.

Inside the bcm.
There are 2 pcbs. The one that carries the fuses looks a bit more heavy duty with fuel pump relay and possibly regulaters.