Arne I think your model will be a lot more than "a little help" here, if for no other reason than that it is an inspiration to get people thinking about the limitations of a mask, to develop one's own criteria, and to find solutions if ready-made solutions are in short supply.
And you hit the nail on the head - it is a difficult compromise between maximum filtration - and still being able to breath comfortably. That is why the cellulose "visor" attached to the glasses seemed to me like a practical accessory. I think your curtain idea could be done better if it were a throw-away replaceable, made from non-woven polyester cloth which is somewhat water repellent, but not an air barrier like sail cloth.
And your 20-minute shopping. Better than any mask or hand sanitiser is simply to stay home unless absolutely necessary for brief periods of shopping, and to try to have no visitors other than the few within your "bubble". If everyone in the world could do that, for a month, it would probably bring this thing to a halt.
I do feel for those who are on the front line and/or have others depending on them, for whom making a Robinson Crusoe adventure out of this pandemic is not an option.