You could achieve this by adding a custom CSS code to your Squarespace site. First, upload the favicon image to your site, then use the :before or :after pseudo-elements in CSS to insert the image into the scrolling text block. Here's a quick example:
.your-scroll-class:before { content: url('your-favicon-url'); margin-right: 5px; /* Adjust as needed */ }
Replace your-scroll-class with the actual class of your scrolling block and your-favicon-url with the direct URL of your uploaded favicon. This should insert your custom icon into the scrolling text.