krunner has been around forever and lets me launch any program (even command line ones) or switch between open windows. It's bound to alt-f2 by default but you can remap it to super-key if that works for you.
No, you cannot remap it to super key, that's the thing. There's an utility for that of course (not in repository and with a lot of dependencies), but out of the box it's not possible.
