Further simplify~ run the following code in console will copy the shortest link form fb.com/1234567890 to clipboard

copy('fb.com/'+[...document.getElementsByTagName("script")].filter(x => x.innerHTML.includes("share_fbid"))[0].innerText.match(/share_fbid":"(.+?)",/)[1])

amazing!

  (function getDebugInfo(flag) {
    const debugInfoObject = {};

    try {
      const debugMatch = document.body.outerHTML.match(/(debug_info":null,"id":")(\w+)/);
      if (!debugMatch) throw new Error("Debug info not found in the HTML.");

      const debugInfoEncoded = debugMatch[2].match(/\S{20,60}/)[0];
      const debugInfoDecoded = atob(debugInfoEncoded);
      const debugInformation = debugInfoDecoded.match(/(\d+)/g);

      if (!debugInformation) throw new Error("Invalid debug info format.");

      const profileAnchor = document.querySelector('.xjp7ctv a.x1i10hfl[role="link"][aria-label]');
      if (!profileAnchor) throw new Error("❌ profile anchor element not found");

      const profileName = profileAnchor.getAttribute('aria-label').replace(/, view story/,'');
      const profileURL = profileAnchor.href.replace(/https:\/\/www\.facebook\.com\//, '').replace(/\?.+/, '');

      const profileID = debugInformation[0] || null;
      const postID = debugInformation[1] || null;
      const postPFBID = (window.location.href.match(/posts\/(pfbid\S+)/) || [])[1] || null;

      debugInfoObject['Profile ID'] = profileID;
      debugInfoObject['Post ID'] = postID;
      debugInfoObject['Post PFBID'] = postPFBID;
      debugInfoObject['Profile Name'] = profileName;
      debugInfoObject['Profile URL'] = profileURL;

      if (flag === "ALL" || flag === 0) console.log("Debug Info Object:", debugInfoObject);
      if (flag === "PROFILEID" || flag === 1) console.log("Profile ID:", profileID);
      if (flag === "POSTID" || flag === 2) console.log("Post ID:", postID);
      if (flag === "POSTPFBID" || flag === 2) console.log("Post PFBID:", postPFBID);
      if (flag === "COMBINE" || flag === 3) console.log("Combined URL:", 'facebook.com/' + profileID + '/posts/' + postID);

      const regex = /(facebook\.com\/(\d+)\/posts\/(\d+)|facebook\.com\/([a-zA-Z]{1}\S+)\/posts\/(\d+)|\/pfbid[0-9a-zA-Z]+)/;
      const match = window.location.href.match(regex);
      if (match) {
        const filtered = match.filter((val, idx) => val !== undefined && idx > 0);
        debugInfoObject['URL Match'] = filtered;
      } else {
        debugInfoObject['URL Match'] = null;
      }

    } catch (error) {
      console.error("Error:", error.message);
    }

    console.log("DEBUG FLAG:", flag);
    return debugInfoObject;

  })('ALL');

Here's another way.

Thx God @JZersche !!!

due to some Facebook updates, this only works if you're not logged in, otherwise it still works but returns some wrong information related too the profileAnchor selecting the wrong profile, and displaying the wrong name. But it still returns the correct post id, and works fine if you're not logged in.