A polyfill for script element loading (for illustration purposes)

script-parsing.js

function parseHTML(getNextElement) {
  let doneParsing = null;
  const whenDoneParsing = new Promise(resolve => { doneParsing = resolve; });

  while (const element = getNextElement()) {
    if (element.tagName !== "SCRIPT") {
      // parse everything else...
      continue;
    }

    const whenSourceLoaded = fetch(element.src).then(response => response.text());

    if (element.async) {
      whenSourceLoaded.then(eval);
    } else if (element.type === "module" || element.defer) {
      Promise.all([whenSourceLoaded, whenDoneParsing]).then(([source]) => eval(source));
    } else {
      eval(await whenSourceLoaded); 
    }
  }

  // This will execute all scripts that are already loaded in the same task
  doneParsing();
}

OK

Do all module scripts actually run before all deferred (if they are loaded by the parse is complete)?

OK actually it was a mistake, was thrown off by "force deferred" script which is a non-standard chromium feature.