I'm using emacs on MAC OSX
ELISP> (emacs-version)
"GNU Emacs 27.0.50 (build 1, x86_64-apple-darwin18.7.0, NS appkit-1671.60 Version 10.14.6 (Build 18G95))
of 2019-09-06"
ielm REPL echoes back the octal, hex and character representation when entering an integer less than or equal to 127:
ELISP> 81
81 (#o121, #x51, ?Q)
ELISP> ?a
97 (#o141, #x61, ?a)
But when using unicode chars like for example lambda ('λ') I get only the number 955
ELISP> 955
955 (#o1673, #x3bb)
ELISP> ?\N{Greek small letter Lamda}
955 (#o1673, #x3bb)
ELISP> ?\u03bb
955 (#o1673, #x3bb)
Since Emacs support full unicode, (you need to use Symbola or some similar font), it should be possible for ielm to echo back the actual glyph for the character:
ELISP> (concat '(?I 32 955 32 ?\u2665 32) "Emacs") "I λ ♥ Emacs"