5k @ 27" is a "sweet spot" for Mac displays, and there's approximately one such display around at the moment - the LG UltraFine - and that seems to have limited availability (especially outside the US).By that, I mean there’s a lot of vendors making monitors… the vast majority cheaper than Apple’s monitor. Are none of those suitable primarily because there’s no Apple logo on them?
There are plenty of other third party displays - but mostly "4k" UHD, and while these are perfectly viable as Mac displays, anything larger than 21" needs "scaled mode" to get sensible icon sizes on MacOS - again, perfectly viable but not optimal.
Then there are features like decent speakers (which Apple does better than anybody else), webcams and USB-C with enough juice to power a 16" MBP that aren't easy to come by.
Except Apple manages to build them into iMacs at affordable (by Apple standards) prices.Maybe inexpensive consumer 220ppi displays aren’t possible?
At one point, you couldn't drive 5k without a messy dual displayport setup, but these days we have DisplayPort 1.4 and Thunderbolt 3 which solve that problem.