Why can't we bring the apps you mention to wayland as a background?
For the foreground, the compositor could even use the alpha channel to draw see through snowflakes: I have foot in quaketerm mode showing what's behind. Replace foot by a smaller snowflake, make more than one of them, and it should be the same!
You can do this to get a matrix wallpaper, this will work with many xscreensaver "utilities"
/usr/libexec/xscreensaver/xmatrix --root
where this is on your distro may be different.