MaterialSkin VS Windows UI Library

I did a quick search and found a WinForms and WPF example of Material Design libraries. It's got some of the same philosophies your examples seem to be looking for.

I wish that was true, but even the new stuff, like their new frameworks, performs poorly while their older frameworks perform really well. That's brand new code, with no legacy codebase to care for.

The reason why I don't recommend Winui is the million bugs it has. See the github issues page. All Microsoft ui stuff sucks currently. But if you use WPF why not FluentWPF

Development for WinAppSdk and WinUI 3 is also very slow and Microsoft seems to not want to push it and invest more developers into it for some reason. They try to improve the framework, is just it's a small team. For example it was a headacke to apply the Mica backgrop and required unmanaged code, they made it simpler and reduced it to a line of code but it took months. I have 2 out of 7 issues fixed on WinAppSdk repository and 0 out of 8 issues fixed in the WinUI 3 repository (some of the older than a year). This are just my issues, there are many other opened by other developers. So yeah, it wasn't fun at all. PoweshellSDK had an issue with the Import-Module command and it wasn't fixed for more than a year and probably won't be ever fixed, but I'm glad I found a workaround, even more clean and more safe, otherwise I couldn't have added the posibility to uninstall and change Store apps.

Compared to UWP or WPF, WinUI 3 is somewhere between 100-200% slower and consumes 7-20 times as much RAM as the old frameworks (for certain operations).