interesting approach.
i know for a fact that something similar to that works with icons, i have posted a tutorial how to do that.
however, i tried using same approach, as i did with icons, with layout.xml (storing it on the M2 card) but it did not work properly.
if you want to try your approach to store fonts on M2 card then path should be something like this "card/tpa/preset/system/fonts/fontname.ttf"
post results please.