Path you can for example: {% Order.OrderItems.FirstItem.OrderItemSKU.SKUImagePath %}
but alias path... , you can get the skuid with macro:
{% Order.OrderItems.FirstItem.OrderItemSKU.SKUID %
} but to get node alias path - you need to write a custom macro to get node based on skuid.
P.S. there is {% Order.OrderItems.FirstItem.OrderItemSKU.Site.DataContext.Documents %}
. Try it to see what it returns.