The reason why I posted this is because there’s nothing that prevents you from using any old screensaver / screenlocker out there in KDE. As I said, I use the Cinnamon screen saver in i3, which is not the Cinnamon environment.
That’s the beauty of Linux: you can mix and match things to your heart’s content.
Ah okay, I didn’t know that. I personally try to stay away from Wayland as long as possible so support for it gets better before I have to jump in. I’m not an early adopter for that sort of thing - even though Wayland is 16 years old at this point, but amazingly it’s still too green for my taste.