Could be that the compose file at  /usr/share/X11/locale/en_US.UTF-8/Compose should include the coding for the normal engineering greek symbols via
the compose-key?
(This is supposed to be the source of the 'compose' key codings (The compose key is labeled <Multi_key> to help confuse people))

This at one time we could get these symbols with g or G  -- <compose_key> <g> <p> would get us π (PI).

There are all sorts of rare charactors in the file - but the Greek letters - like π (PI) - are not assigned a compose key sequence ..
instead by a <dead_greek> key.

If I run xmodmap -pke |grep -i dead_

I see there isn't a greek dead-key assigned.

This rather normal set up should allow one to type Greek symbols 'out of the box'.

The file at /usr/share/X11/locale/en_US.UTF-8/Compose belongs to libx11-data - but I don't see that it is open?

Hi,

I saw something similar so decided to share it here. Maybe it will help you.

I have this in my /usr/share/X11/xkb/symbols/us

   key <TLDE> { [     grave, asciitilde,    dead_grave,       dead_tilde ]
};
   key <AE06> { [         6,asciicircum, dead_circumflex,     dead_caron ]
};
   key <AE11> { [     minus, underscore,   dead_macron,           degree ]
};
   key <AD11> { [ bracketleft, braceleft, guillemotleft, dead_doublegrave ]
};
   key <AD12> { [bracketright, braceright, guillemotright, dead_doubleacute
] };
   key <AC11> { [apostrophe,   quotedbl,    dead_acute,   dead_diaeresis ]
};
   key <AB08> { [     comma,       less,  dead_cedilla,      dead_ogonek ]
};
   key <AB10> { [     slash,   question,  questiondown,      dead_stroke ]
};
   key <BKSL> { [ backslash,        bar,    dead_greek,        brokenbar ]
};
   key <LSGT> { [ backslash,        bar,    dead_greek,        brokenbar ]
};

(from https://www.choam.eu/altgr-intl/#weur)

Running setupconf gives me 8 warnings:

Mar 10 15:36:22 msi console-setup.sh[560]: WARNING: Unknown X keysym
"dead_greek"
Mar 10 15:36:22 msi console-setup.sh[560]: WARNING: Unknown X keysym
"dead_greek"
Mar 10 15:36:22 msi console-setup.sh[560]: WARNING: Unknown X keysym
"dead_greek"
Mar 10 15:36:22 msi console-setup.sh[560]: WARNING: Unknown X keysym
"dead_greek"
Mar 10 15:36:22 msi console-setup.sh[560]: WARNING: Unknown X keysym
"dead_greek"
Mar 10 15:36:22 msi console-setup.sh[560]: WARNING: Unknown X keysym
"dead_greek"
Mar 10 15:36:22 msi console-setup.sh[560]: WARNING: Unknown X keysym
"dead_greek"
Mar 10 15:36:22 msi console-setup.sh[560]: WARNING: Unknown X keysym
"dead_greek"

dead_grave, dead_circumflex, dead_tilde, dead_acute, dead_cedilla, and
dead_diaeresis work as intended on the console, the other dead keys spit
out the normal characters. In X all the dead keys work as intended.

Did you check your logs?

My system: