URL replace rules

We are using WordPress as a headless CMS. And some of the paths used in content are replaced in wp-json output. Like images come from CDN, or even the site base url is different for the JSON.

1) Would be nice to add a custom base url when the wp-admin is at foo.bar/wp-admin and the site is at site.com so that the relative urls would be correct.

2) Would like to add url replace rules for example when the images are in CDN. So that your plugin would check the CDN path for the same image.