The way they talk about it makes it sound like they invented the written word, but that notwithstanding the fonts actually look really nice in my opinion.
It's a cool idea and the example they gave actually seemed pretty neat.
I'd (somewhat perversely) love to see this feature tried in a terminal emulator.
ANSI does actually define escape codes for switching to alternative fonts (ESC [ 10 m through ESC [ 19 m) though I don't know of any software or even term drawing library that uses it.
Kitty terminal has a lot of configurations for fonts. I beleive you can get down to adjustments for specific charecters. Idk if it uses the specific technology you are suggesting. But it is explained in the kitty.conf docs.