Além de Alt + Shift para mudar o layout do teclado, outras combinações de teclas do Xorg?

Tudo o que posso encontrar sobre o XkbOptions foi:

Option "XKbOptions" "grp:alt_shift_toggle"

Parece que só posso usar alt+ shiftcombinação para mudar o layout do teclado, outras teclas que posso usar?

De man xkeyboard-config:

Teclas para alterar o layout

   ┌───────────────────────────────────────────────────────────────────────────────────────────────────────────┐
   │Option                      Description                                                                    │
   ├───────────────────────────────────────────────────────────────────────────────────────────────────────────┤
   │grp:switch                  Right Alt (while pressed)                                                      │
   │grp:lswitch                 Left Alt (while pressed)                                                       │
   │grp:lwin_switch             Left Win (while pressed)                                                       │
   │grp:rwin_switch             Right Win (while pressed)                                                      │
   │grp:win_switch              Any Win key (while pressed)                                                    │
   │grp:caps_switch             Caps Lock (while pressed), Alt+Caps Lock does the original capslock action     │
   │grp:rctrl_switch            Right Ctrl (while pressed)                                                     │
   │grp:toggle                  Right Alt                                                                      │
   │grp:lalt_toggle             Left Alt                                                                       │
   │grp:caps_toggle             Caps Lock                                                                      │
   │grp:shift_caps_toggle       Shift+Caps Lock                                                                │
   │grp:shift_caps_switch       Caps Lock (to first layout), Shift+Caps Lock (to last layout)                  │
   │grp:win_menu_switch         Left Win (to first layout), Right Win/Menu (to last layout)                    │
   │grp:lctrl_rctrl_switch      Left Ctrl (to first layout), Right Ctrl (to last layout)                       │
   │grp:alt_caps_toggle         Alt+Caps Lock                                                                  │
   │grp:shifts_toggle           Both Shift keys together                                                       │
   │grp:alts_toggle             Both Alt keys together                                                         │
   │grp:ctrls_toggle            Both Ctrl keys together                                                        │
   │grp:ctrl_shift_toggle       Ctrl+Shift                                                                     │
   │grp:lctrl_lshift_toggle     Left Ctrl+Left Shift                                                           │
   │grp:rctrl_rshift_toggle     Right Ctrl+Right Shift                                                         │
   │grp:ctrl_alt_toggle         Alt+Ctrl                                                                       │
   │grp:alt_shift_toggle        Alt+Shift                                                                      │
   │grp:lalt_lshift_toggle      Left Alt+Left Shift                                                            │
   │grp:alt_space_toggle        Alt+Space                                                                      │
   │grp:menu_toggle             Menu                                                                           │
   │grp:lwin_toggle             Left Win                                                                       │
   │grp:rwin_toggle             Right Win                                                                      │
   │grp:lshift_toggle           Left Shift                                                                     │
   │grp:rshift_toggle           Right Shift                                                                    │
   │grp:lctrl_toggle            Left Ctrl                                                                      │
   │grp:rctrl_toggle            Right Ctrl                                                                     │
   │grp:sclk_toggle             Scroll Lock                                                                    │
   │grp:lctrl_lwin_rctrl_menu   LeftCtrl+LeftWin (to first layout), RightCtrl+Menu (to second layout)          │
   │                                                                                                           │
   └───────────────────────────────────────────────────────────────────────────────────────────────────────────┘

Funciona como um encanto Openbox 3.6.1 Ubuntu 18.04:

 $ setxkbmap -model pc105 -layout us,ua -variant qwerty -option grp:win_space_toggle