To successfully deploy SFRA code to a developer sandbox ensuring that the site appears and functions as designed, the developer should execute the following build steps: npm run compile:js, npm run compile:scss, and npm run compile:html. These commands compile JavaScript files, SCSS (Sass) files, and HTML templates respectively, which are essential components of the storefront application. This sequence ensures that all the necessary frontend assets are properly compiled and ready for deployment, aligning with SFRA's architecture and build requirements as outlined in the Salesforce B2C Commerce documentation.