Tapper
Keyboard layout switcher for X Widow System and Wayland
Тapper — keyboard layout switcher for X Window System and Wayland. Tapper runs in background, when an assigned key is tapped, Tapper activates the corresponding keyboard layout.
"Tap" means that a single key is pressed and quickly released, so (1) no other keys are pressed at this time, and (2) period between pressing and releasing is shorter than keyboard repeat delay (usually it is 0.5 s, but it depends on desktop settings).
Tapper key feature is using modifier keys for switching keyboard...