The Zero gravity chair is an interesting option.
Tried it, Cranial pressure problem..
When you support your neck, you apply pressure in the ventral direction against the neck..
This pressure can be felt over extended use.. leading to headache/ blurry vision
Sorry, can't let your findings stand as a notice of complete and authoritative knowledge on the topic. I understand you may have experienced these cranial pressure issues, but I can personally attest to the fact that they do not affect everyone.
I also fancy myself an ergonomics expert. As I mentioned, I thoroughly invested in this matter for my own needs and have found no major issue with cranial pressure.
Additionally, there is a product called prism glasses for the elderly which allow them to lay completely flat out in corpse pose otherwise known as shivasana in yoga. Using these glasses, injured or elderly persons may read or watch television. I also used these glasses extensively and found that while in the first day or two there is some mild dizziness due to cranial pressure issues, they subside completely thereafter, at least for me. If such cranial issues were so dangerous as to cause a stroke hazard, the product wouldn't be on the market for the last 20yrs.
Your findings serve as a good notice of possible side effects, but I don't feel it's legit to authoritatively state that something some of us have found to be viable and extremely helpful to our daily routines is dangerous. It may be for some, but not for all of us
Full disclosure, I have a vested interest in my name as an ergonomics expert, having built what I have found in my investigation, building, and diligent testing to be the best game controllers available for middle-aged folks. Game controllers that allow us older guys to continue gaming without gradually creating RSI or other problems.
Although nobody really pays attention to my game controller work other than a few friends on this forum whose attention and friendship I greatly value, I'd be lying if I said that I don't someday kinda hope to make a company called Zero Impact Gaming. It is for these reasons that I don't adore having a solution I've developed over the course of 10 years be stated to be dangerous and nonviable. I'm sure you can understand that