WordPress
Add your exported widget to a WordPress site.
These steps work for most WordPress sites. Your theme or host may label things differently.
Upload the file
Export your pet as a JS file from the builder. Upload it to your site — for example with your host's file manager or SFTP, into your theme or the web root — and note its URL.
Add the script
Add a script tag pointing at that URL to your site's footer. Many themes have a "footer scripts" setting; otherwise a header-and-footer code plugin works.
<script src="https://your-site.com/pixel-widget.js"></script>