AMP GA tracking get additional information on click events

Question

I've inherited a legacy setup for GA tracking in AMP and attempting to add link click tracking. I am following this example and the link click is coming through. It has been requested that we also track the page URL and the link URL. I see a handful of other variables/parameters in our setup. I'm wondering if there's a library that has all the available variables listed or what I might use to get the extra information on a link click.

These are the current triggers we have in place:

"triggers": {
  "page_view": {
      "enabled": true,
      "on": "visible",
      "request": "ga4Pageview"
  },
  "performanceTiming": {
      "enabled": true,
      "on": "visible",
      "request": "ga4Event",
      "sampleSpec": {
          "sampleOn": "${clientId}",
          "threshold": 100
      },
      "vars": {
          "ga4_event_name": "performance_timing"
      },
      "extraUrlParams": {
          "event__num_page_load_time": "${pageLoadTime}",
          "event__num_domain_lookup_time": "${domainLookupTime}",
          "event__num_tcp_connect_time": "${tcpConnectTime}",
          "event__num_redirect_time": "${redirectTime}",
          "event__num_server_response_time": "${serverResponseTime}",
          "event__num_page_download_time": "${pageDownloadTime}",
          "event__num_content_download_time": "${contentLoadTime}",
          "event__num_dom_interactive_time": "${domInteractiveTime}"
      }
  },
  "linkClick": {
      "on": "click",
      "selector": "a",
      "request": "ga4Event",
      "vars": {
        "ga4_event_name": "link_click"
      },
      "extraUrlParams": {
        "page_location": ??,
        "link_url": ??
      }
  }