Hello @MitsuhaKitsune and welcome to the forum!
That’s too bad! So, if Android doesn’t pass installed fonts in addition to the system fonts to the installed apps it becomes problematic. I can’t tell you if your idea, your wish is feasible, but since Google is “closing” the file system of Android more and more, I think it is at least a very difficult task to implement.
But you can of course create a feature request, maybe then you will learn more about a feasibility?
Michelist