I have an English US keyboard (it has an Alt on the right of the spacebar), I have set the English US Layout and if I use "Show Keyboard Layout" and press the right Alt the key on the right (labeled as Meta R, Alt R) gets highlighted. However, in Emacs it is not recognized as Meta, and in xev it shows as ISO_Level_3_Shift. The computer is dual booted with Windows, and the right Alt is properly recognized there.
The output of gsettings get org.gnome.desktop.input-sources xkb-options is @as []
