Can I include a gallery of my other items as part of a listing template?

Yes, you can use the following Cross Selling Widgets in your listing template: 

• most recent items - your latest additions
• items ending soon - your listings sorted by end date
• featured items - marked as featured in WooCommerce
• related items - WooCommerce cross-sells or up-sells

These can be inserted in your listing template just like any other shortcode. 

For more details, check out the list of shortcodes on the edit template page or see  https://www.wplab.com/plugins/wp-lister/documentation/templates/#TemplateShortcodes.