This is a plugin for Ulauncher that lets you search & switch between Linux/X11 Windows by name:
The default keyword in win, so just run Ulauncher, then type win <query> to filter the window list, then select a window from the list to switch to that window.
I used window icons from the Obsidian Icon pack
You need wmctrl installed. See: https://www.freedesktop.org/wiki/Software/wmctrl/
For Debian/Ubuntu, you can do:
$ sudo apt install wmctrl