Add public link to invoice in email template

since it is still not possible to attach invoices as PDF to emails, we would like to add a link to the invoice in the email-template. I tried to accomplish it with something like this:

 <a href="{{ order.token }}">Download Invoice</a>

The link is created correctly. But when the user clicks on the link, they are required to login to the snipcart dashboard.

Are the invoices available publicly without login somewhere?
There doesn’t seem to be an API endpoint for invoices, at least it is not documented.