WP 5.6 will ship with jQuery 3. It will also include jQuery Migrate 3, so this change should not impact WooCommerce JS code in any way. That being said, we need to start working to make sure our code is fully compatible with jQuery 3 as WP plans to remove jQuery Migrate 3 in a future version (WP 5.7 or later).

I don't think there is a way to search all our codebase automatically and get a list of functions that we are using that were deprecated in jQuery 3 (similar to what we normally do with PHPCompability when checking for compatibility with a new version of PHP). So I guess we will either have to get the list of jQuery 3 changes and search for deprecated code manually or monitor the dev tools console while browsing WooCommerce related pages and fix deprecated code as it is reported by jQuery Migrate. Please let me know if there is a better way to approach this.

I'm planning to split this epic into two issues. One to address WooCommerce JS code and another one to address external JS libraries that are shipped with WooCommerce.