Interesting I have never thought about this.
I just looked at the nodes source code and it seems n8n is using a package to find all of the system fonts. So likely just a matter of getting a font installed in the container.
The way to do that (if i were to make an educated guess) would be to edit n8n’s Dockerfile to make your own custom image that preinstalls your font when the image is built.
This is a pretty complex process if you aren’t experienced with docker or IT
here is a resource on adding fonts to alpine (which is the image n8n is built on).