Is there a way to create a shortcut that does the opposite of Super+H?
Super+Up only works on a window that has not been minimized.
I also tried Alt+F10 and Super+Down, but no luck.
gsettings get org.gnome.desktop.wm.keybindings restore returned no results.
Is there a way to create a shortcut that does the opposite of Super+H?
No. Shortcuts like Super+h, Super+Up/Down all act on the currently focused window. Hiding a window moves the focus elsewhere, so any “Unhide” shortcut would act on the wrong window (which by definition isn’t hidden, so there’d be nothing to unhide).