I've been using it on my nVidia Shield for a while now. No ads, a lot of UI customisation, and Sponsorblock is integrated as well.
I previously used my PS4 for watching everything, but having a full desktop OS is just way better: I can browse the web on my TV, control it remotely with my laptop's keyboard and mouse using Barrier, open multiple live feeds in picture-in-picture mode, play music in the background of whatever I'm watching, etc. Also, when I'm watching sports and they go to a side-by-side commercial break, I use the zoom accessibility feature to zoom in on the tiny live feed so I can watch that full screen without seeing any ads haha.
I'd be curious to know more about how you configured KDE. I run a pretty vanilla Pop OS setup right now, which is more usable than I expected with my USB remote, but I've been meaning to explore how to set up something more "smart TV"-like that's a bit easier to navigate. My initial thought was to write a browser extension or a custom app with an embedded browser, but that feels like a bit too much work for something that's supposed to be a leisure/entertainment setup.
I also configured font sizes, cursor size and mouse acceleration for usability. It works really well.
Would you share the details of the hardware setup (MiniPC, USB remote control) and screenshots of your configured KDE/Plasma desktop?