I agree @jmangelo . I had earlier considered templating for these values at build time (where the JS scripts would be bundled) on a build agent, but the problem is that it doesn’t make the output build bits environment agnostic.
Suppose I’m using Azure with two slots in production each slot having their own environment variables with these values, it won’t play out since these values would then be hard-coded at build time. So I’m going with a public API route which would then return the values based on each environment’s own variables.