Not parent poster but, as somebody who works on macOS, my problem is that the switch between the high-density laptop screen and a “pixelated” external one is extremely jarring. At one point I had an additional, average Dell monitor and every time I moved my eyes I cringed. After a couple of days I just removed it - better to have fewer screens than forcing my eyes to readjust every few minutes.

So yeah, if your primary device is a modern Mac, you really want a high-res, high-density screen.