We could use:
https://github.com/mozilla/pdf.js/blob/c3d08580627471432a6ad0b2fdb948df64126afa/src/display/api.js#L929

and look at bit 4.

The following pdf:
https://orimi.com/pdf-test.pdf
is not editable in neither Acrobat nor Edge nor Foxit and nor Okular.
const config = getViewerConfiguration();
  if (typeof PDFJSDev === "undefined" || !PDFJSDev.test("PRODUCTION")) {
    if (window.chrome) {
      const link = document.createElement("link");
      link.rel = "stylesheet";
      link.href = "../build/dev-css/viewer.css";
      document.head.append(link);
    }
    Promise.all([
      import("pdfjs-web/genericcom.js"),
      import("pdfjs-web/pdf_print_service.js"),
    ]).then(function ([genericCom, pdfPrintService]) {
      PDFViewerApplication.run(config);
    });
  } else {
    if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("GENERIC")) {