Yes, yes. I actually did that, and i forgot about this post (in GH and in here 
)
But yes, i was able to do it. I patched my sans font and my mono font and added them on the userchrome.css. And it worked, as i presumed.
The issue i faced was that this would only show the glyph on my Linux, not on the android. So i found a module to change the android font, and patched all my system fonts, too. So now i got the glyphs in all my devices. It is looking stunning.
Would be nice to have this as a default feature though, of course. But being possible to do it like this is nice already!