I wonder if you can load a font from base64 string like you can with images. Then, one may write a pure js library which generates such font from a set of rules on the fly. Catered to a specific use case.
@font-face {
font-family: 'foo';
src: url(data:application/x-font-woff;charset=utf-8;base64,d09GRgABAAAAAGy …)
}(E.g. see https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_...)