Hey, so the turn signal stalk is all wired up and works! It I also have wiper control button working exactly as it does on the 3/Y, and flashing brights by pulling back on the stalk works as well. I rarely used the pushing forward motion in my 3 to enable/disable automatic brights, so instead I actually made that into a Homelink trigger, and it is absolutely awesome.
I'll need time to get it written up, and there is some basic soldering involved. I'm using a Particle Photon + Carloop to read the state of the stalk and send CAN messages to the car, so nothing stock is modified and the change is entirely reversible. I'll create a git repo with the instructions to recreate the work and a BoM.
Note: I have zero interest in selling or supporting this, so it will be an entirely DIY endeavor if folks want to do it. However, I do expect that approx 3 days after I publish the info, you'll be able to buy one on alibaba.
This is an UNLISTED youtube link, so please don't share beyond the forum for now. I am planning to do a better quality video about the project soon.