If you're using a Mac, you're probably familiar with emoji. vim-emoji (GitHub: junegunn / vim-emoji) by Junegunn Choi makes it easier to work with emoji in Vim. The author's examples include settings for Git Gutter.
The plugin provides a function that can be used to look up an emoji symbol, like this:
emoji#for('small_blue_diamond'). That means you could tie it into anything you want: perhaps a
Some plugins and settings benefit from special casing based on the current font. I dimly recall running into this when writing small scripts that enhance the old Powerline. fontdetect (GitHub: drmikehenry / vim-fontdetect) by Michael Henry tries to improve on Vim's
if fontdetect#hasFontFamily("DejaVu Sans Mono") let &guifont = "DejaVu Sans Mono 14" endif
It should work with GTK, Mac OS X, and Windows, so it might help you add a bit of portability to more extreme uses of textual UIs.