Yea, we can probably keep a head alive by itself for a short period, I suspect as you pointed out that the “immediate risk of dying from a complication” means if we attempted it the first person wouldn’t even last weeks or months.

The ethics of doing so on the other hand are stupidly complicated, which deters almost all effort in the development of this kind of system. You couldn’t ethically do it to anything smarter than a pig without huge problems, and you may even have trouble with that.

I’m honestly surprised we haven’t seen any hint of this coming out from some random billionaire funding a bunch of doctors to work on it behind the scenes. I’m sure there are doctors who for the right price would be willing to move to some country with less-stringent regulations and attempt some tests on chimps.