Ok a bit flippant, but I've been running KDE on my NUC as a secondary desktop for years now. Most of the time it works fairly well, but then suddenly something breaks or needs tweaking. And when it does it's often not trivial for a non-geek to handle.
That said, if they can get Krdp working properly, I'll almost certainly switch to KDE as my main driver, and demote Windows to my secondary.
Assembled PCs tend to be more compatible (because of more standard components), but on the othe hand each individual component doesn't receive the coverage (testing) as laptops. There was no way for me to know that my mobo's sleep is broken on Linux, even if the previous mobos from the same producer had good compatibility.
I've never even heard of Ubuntu certification. I instead search for people who are using the product I wish to buy with Linux, and see what they say about its compatibility. This always works. So it is not pretty much impossible.
I'm not sure if you refer to friends or strangers on the internet.
In the former case, one is restricted to a very small pool of models to choose from.
In the latter case, "strangers on the internet" who say that their hardware "works perfectly", are typically completely unreliable; saying "my hardware works perfectly is treated as a badge of honor, so there's a perverse incentive.
One example, in a lot I've personally experience, is that I've read from multiple "strangers on the internet" that the wifi from the laptop I'm typing from, "works perfectly". In reality, the Linux drivers are half broken (on Linux, it has a poor signal).
On Windows, on a clean install, I need to install the drivers from WU to get audio working, etc. And then I need to open Intel website to get the latest Bluetooth driver, go to Dell to get the latest wifi, as on Windows Update's these are not the latest.
And even after all of this, some of the drivers on Linux is better maintained, because the support for old Intel GPUs on Windows is very short. Meanwhile, on Linux, I get Vulkan support, and all recent drivers on my Broadwell. Video perf is way better on Linux here.
[1] https://askubuntu.com/questions/1407494/screen-share-not-wor...