And when I choose 'Water Closet' under transport-sign (which is a new
method to me ;-), it is inserted B/W.  The character itself is taken
from the font:

            character: 🚾 (displayed as 🚾) (codepoint 128702, #o373276, #x1f6be)
              charset: unicode (Unicode (ISO10646))
code point in charset: 0x1F6BE
               script: emoji
               syntax: w 	which means: word
             category: .:Base
             to input: type "C-x 8 RET 1f6be" or "C-x 8 RET WATER CLOSET"
          buffer code: #xF0 #x9F #x9A #xBE
            file code: #xF0 #x9F #x9A #xBE (encoded by coding system utf-8-unix)
              display: by this font (glyph code):
    harfbuzz:-outline-Segoe UI Emoji-medium-normal-normal-sans-12-*-*-*-p-*-iso10646-1 (#x1882)

I tried to install Noto Color Emoji from here[1] but the
WindowsCompatible ttf still doesn't work under Win10 (Ver 21H1, 19043).

Any chance to get colors with Segoe?

Best, Arash

Footnotes:
[1]  https://github.com/googlefonts/noto-emoji/tree/main/fonts