If you decide to give the user the choice to easily configure a theme, than you should go with package.json options and translations.
You probably have some pagesets, some pagination, some background images, and other stuff that a user may want to modify. A configurable theme give the user the ability to modify the theme to their needs in one place, in their config.php in the project root.
The advantage of this is, a user don't need to hardcode into the theme. Your theme is far more flexible.
If you decide to use a config, than add an
option section to your