A small utility that does one thing: switches the keyboard layout you ask for.
Each group is an ordered list of layouts with its own shortcut. A repeated press moves to the next one and wraps around.
Press the field and then the keys. Any combination with ⌘, ⌥ or ⌃ works, and two groups never share one.
The familiar list appears on screen with every layout of the group. Show it always or only for more than two layouts, in glass, or solid with a transparency you choose.
One switch in the menu bar menu turns Langouste off, and the system shortcuts take over again.
No window and no Dock icon. Settings open from the menu bar icon.
One app for Apple silicon and Intel on macOS 12 or later. It needs no account, and the only request it makes is a daily check for updates, which you can switch off.