Can I connect to our site, via ajax, on behalf of the account owner and pull a booklet list? Shopify Theme app extension - App Block

I am creating an app block with theme app extension with a select menu for the online store. The goal is to allow users/merchants to install our app, add the app by using Add Block and then hit the select menu and select a booklet/pdf from our site to embed on their storefont in Shopify. 

I am currently using Shopify CLI 3.0 and have the app installed to our store with the select menu (on the right panel) but the values are hardcoded at the moment.

I wanted to know: 

1. Can I connect to our site, via ajax, on behalf of the account owner and pull a booklet list?
2. Can I dynamically update the drop-down menu with that booklet list?

I have the liquid file for the block looking like this:

app-block.liquid:

<iframe src='https://louddoc.com/embed.php?wpKey={{ block.settings.workpad_key }}&source=embed' allowfullscreen width='100%' height='1220' style='border: 0; overflow: hidden; width: 1px; min-width: 100%; max-width:950px;' scrolling='no'></iframe>

{% schema %} 
 { 
  "name": "Title for App", 
  "target": "section", 
  "stylesheet": "app.css", 
  "javascript": "app.js", 
  "settings": [ 
    { 
     "type": "select", 
     "id": "workpad_key", 
     "label": "Embed your booklet to your store", 
     "options": [ 
       { 
          "value": "5xsYPWgs3l3VbOK1izBx6j", 
          "label": "Booklet 1" 
        }, 
        { 
          "value": "C8Ij8PqtVpDvVpVNVXDQhw", 
          "label": "Booklet 2" 
        }, 
        { "value": "hLxVnSxFJuLw3iCvpfLko1", 
          "label": "Booklet 3" 
        } 
       ] 
      } 
     ] 
    } 
{% endschema %}```