And get a list of characters in a font like this:

Here is a method using the fontTools Python library (which you can install with something like pip install fonttools ):

I'm looking to see if there is a way, in PHP, to determine if a glyph exists for a given character in a font.

Here is a method using the fontTools Python library (which you can install with something like pip install fonttools):

A Glyphset is the glyph repertoire of a font, i.e. all glyphs present in the font. The old term for this repertoire was “character set”, but it is misleading because in modern font technology, a font is a collection of glyphs, not a collection of characters.