This may interest someone.
https://www.businessinsider.com/how-united-new-economy-bed-called-relax-row-will-work-2026-3
Looks like a copy of Air New Zealand's SkyCouch.
My grown son and I bought the extra seat on NZ Air, but didn't make it up into a bed, just used it for extra room. The woman in front of us looked very comfortable in hers.
Turkish air tried this a few years ago. Didnt last long.
The last 10 years, about half the times I have crossed the atlantic I have had the good luck to find three seats in the center section. I just move to them and stretch out. Never a problem. But I am just as good leaning my seatback as far as it will go.