>>106478250
>>106478309
>>106478363
Maybe what you're looking for is Oxygen theme in KDE Plasma? It's still fully supported in KDE Plasma 6, you just have to install a separate distro package, usually called "plasma-oxygen" or so, then switch your theme and icons to it. Unlike the other bullshit Plasma themes you get from the "Plasma store", this one is actually well made because it used to be the main theme.

>>106478347
Haiku is also a good option, will be amazing when it releases. Unfortunately it won't really be able to handle gaming, but for web browsing, media playback, stuff like that it will be phenomenal.