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.
!this.container.offsetParent ||
      this._getVisiblePages().views.length === 0
    ) {
      return Promise.resolve();
    }
    
    
    const visibilityChangePromise = new Promise(resolve => {
      this.#onVisibilityChange = () => {
        if (document.visibilityState !== "hidden") {
          return;
        }
        resolve();
        document.removeEventListener(
          "visibilitychange",
          this.#onVisibilityChange
        );
        this.#onVisibilityChange = null;
      };
      document.addEventListener("visibilitychange", this.#onVisibilityChange);
    });
    return Promise.race([
      this._onePageRenderedCapability.promise,
      visibilityChangePromise,
    ]);
  }
  /**
   * @param {PDFDocumentProxy} pdfDocument
   */
  setDocument(pdfDocument) {