While SWEs might need/want a good desk setup, many office jobs just don't need it. I'm not sure people are really improvising but rather find sitting with a laptop is how they normally work anyway.
And working in the bedroom can be misleading... it's often a private place you can put a proper desk.
I WFH and went from living alone to having 3 roommates who all WFH. I have my bed, desk, and theater setup all in the (master bedroom). It's actually better than a 1bdr apartment, it's quieter (no leafblowers!) and I don't have dirty dishes right behind me.
I have a small desk but a 4K 32" monitor and a vertical 1080p one. A microphone on an arm and NO webcam; I use screen sharing 90% of the time but I don't need to see peoples faces. (I really wish video calling didn't compress >1080p screens so much). If I need a webcam, I use my laptop.
Maybe the pandemic changed things but you could get decent chairs for $20 at goodwill.
I guess I'm just skeptical that a majority of people have difficulty working from their home... You know the place you live and pick your own furniture.