I just went to Preferences and set the resolution of the virtual display to 1920x1080.

But doesn’t that affect ALL windows?

Yes, and? You only need to move the window you want to share to that, and at that resolution, without retina, things are pretty readable.

I like the idea! Rooting for whoever in the universe working on it! Meanwhile, I think you could actually "mimic" this by using OBS as a virtual camera and use multiple layers to selectively share windows. You can set an output video size, and scale different layers/windows individually.