I love being able to create and track invoices with Monzo. And the recent update allowing PDF generation is ideal! I currently use the Monzo Xero integration to reconcile my statements. But I have to create the invoice in both Monzo and Xero at the moment so I can reconcile incoming payments in Xero, which is annoying. I’ve seen that Xero have an API endpoint that allows creating invoices programmatically. It would be amazing if invoices created in Monzo (draft or otherwise) would sync with Xero so I can remove the overhead of creating the same invoice twice.
Doesn’t Monzo already offer Xero integration or is this something different?
Monzo export your transactions to Xero only as far as I’m aware. Unless I’m missing something, invoicing is managed by Monzo and not integrated with Xero. I’d love to be wrong and find that there is a magic switch I’ve missed.
I’m not sure because I don’t use it 
Hopefully someone else can help clarify.
If you’ve found it in the API you could always hire a developer to build it for you. If it saves you lots of time it should be worth the cost.