I use a single ultrawide at home and dual-monitors at work.
Initially thought having one monitor experience was more seamless, but I do miss implicit window organizational aspect that dual monitors provide. And screensharing on the ultra-wide is a pain.
If your ultrawide is anything like mine, it also has a setting that lets it register as two separate monitors (PIP/PBP mode), which is like having two monitors without the bezel, but with the convenience of "there's an edge" in the middle of your screen when doing regular desktop work.
Does require two cables of course, but if you're driving an ultrawide, you're probably using a graphics card with three or four outputs anyway.
My Samsung ultra wide has side by side mode with two input cables. Screen sharing (and Windows) thinks it’s two monitors but I can stretch windows all the way across both if I want to since it is an extended set
Best of both worlds, I wish there were a way to configure this within the OS so that you could make a single screen appear like 2, 3, or 4 logical screens.
A decent window management tool (e.g. Rectangle.app) should resolve most of your window management issues - set up many drag points to easily divide windows by half, thirds, quarters, sixths, etc.
Most screen share apps should support sharing by window. Also best for privacy (so your viewers don't see the side channel chat notifications pop up).
Also an ultrawide monitor is preferable for spreadsheet warriors.
I will not give up my 49" 21x9 for anything lesser.
Initially thought having one monitor experience was more seamless, but I do miss implicit window organizational aspect that dual monitors provide. And screensharing on the ultra-wide is a pain.