Manjaro-Deepin contains a small selection of screensavers out of the box, and you can change them by right-clicking the Desktop and picking "Wallpaper and Screensaver". There are no more than 10 screensavers, and they're all XScreensaver classics - but not the ones I like.
I forget whether Manjaro has Xscreensaver as a dependency, or whether I just installed it out of frustration, but all the screensavers are there - just not showing in the regular Screensavers option. Manjaro-Deepin also has its own screenie daemon, with no need to use XScreensaver.
I had to move all the XScreensaver screenies over to Manjaro-Deepin's screensaver folder. Unfortunately, without thumbnails (which makes things confusing, as Deepin doesn't use screensaver names). Is there not a package that does this automatically? There should be! Perhaps @oberon could take note?