Very interesting. And there are tDCS home kits for $149, e.g. https://apexdevice.net/shop/apex-type-a-4ma-std/. This is low cost enough that I'm willing to give it a shot. Worst case, I end up with a decent DC current source that I'm sure I can find a use for at some point.
Okay, sounds like some people trying this at home have had seriously bad side effects. So will definitely have to do some reading before giving this a shot.
Here is a great comparison of noninvasive brain stimulation techniques for depression treatment: https://www.bmj.com/content/364/bmj.l1079
A company that offers tDCS as a home treatment for depression can be found here: https://flowneuroscience.com/