The iGPU on my 9950X is perfectly capable of driving my Dell U4025QW 5k2k ultrawide. Yeah it would suck for any modern 3D games, but for productivity or light gaming it's fine.

It requires I use the DisplayPort out on Linux because I can't use HDMI 2.1. Because the motherboard has only 1 each of DisplayPort and HDMI this limits my second screen.

It works fine with intel and amd igpu's. They won't run many games at the native resolution though. Doesn't really matter to me, as the igpu's are in work laptops for me, so 60hz or better passes for "adequate".

Even a raspberry pi 4 or newer has dual 4k outputs, that can fill the entire screen at native resolution. Macs have been the worst to use with it so far.

I don't have one, but I suppose it would be just fine if you only use it for running a desktop environment.