Sorry for bumping this post but it seems to be along the same subject I am suggesting so I just post here…
I am thinking if it would be possible to implement variables that generates glyph maps for the font files like {glyphmap_basic_latin} to generate something like this
{glyphmap_private_use_area} will generate glyphs from the PUA range, etc:
And there may be fonts with alternates that stored uncoded will be something like {glyphmap_uncoded}… You can also define the number or columns per row in the setting