The power folding mirrors I found apparently don’t have LEDs for blind spot monitoring, was hoping I could swap the wiring and mirror glass over to the power folding ones to have BSM on them.
If you buy the AliEx folding mirror kit without BSM wires, and you spend the extra $44 to buy the AliEx BSM wiring kit (just the wires), you get the wires you need to plug into the factory mirrors with BSM symbol glass. What you don't get are the two plugs to mate into the factory 2-pin plugs (1J0-973-119) used on my Mk7.5 near the door modules. I had to source those separately, and wait another month or 6 weeks... You'll also want a crimp tool to crimp those little connector terminals.
The wires that light up the LEDs come from the BSM modules and go directly through the door hinge up into the mirror housing (folding or not). At least from my recollection, they don't have a "stop" at the connection point located inside the door.
(Also, shameless plug for some BSM modules and mirror caps
I have for sale here.
My recollection differs, but maybe it was just a Mk7.5 thing? The AliEx wiring kit I bought was intended to go from the door hinge directly to the mirror housing. The 2019 Mk7.5 I own (with factory BSM) came with 2-pin plugs near the door modules that allow you to detach the mirror without having to rape the door hinge connector. However, the AliEx wiring kit I bought was as you describe, straight from the hinge to the mirror and didn't include those 2-pin connectors near the door modules. Looking through the photos in my phone it appears to be a 1J0-973-119.