JOINS can be chained and combined with UNNEST as many times as desired.
In the example on the right we perform an in-document join to generate a complete order that contains the order Ids along with the users details. This is then JOINED with the order decriptions from the users_with_orders bucket.
SELECT u.personal_details.display_name name, s as order_no, o.product_details
FROM users_with_orders u KEY "Aide_48687583"
UNNEST u.shipped_order_history s
JOIN users_with_orders o KEY s.order_id