Externalize app.config.js so code doesn't contain environment specific settings

Is there a way to externalize the app.config.js? We would like to be able to have a known location for the config file on each box (eg. /siteconfig/app.config.js) that the built expo web website code just refers to. That way the website code that we ship to each box would be the same regardless of the environment. Right now it has the config embedded in the website js code.