It would be good to have a way to choose which fonts might substitute the fonts that the user does not have in their device or computer.

In my project, I am creating a module that uses Lato font. When opened in mobile, it substitutes for Georgia, but this is not the best option. In my case it would be best substituted by Arial.

You should create a form of hierarchy in the Font palette, where you choose the fonts that will substitute the fonts in your project.