Invoice/Quote - Approval Process for Quote/Invoice Maker/Checker
Have a maker and checker workflow for quotes and invoices, allowing a single user to toggle between situations.
Eg. User A draft quote/ invoice -> submit to User B for approval -> Once approved, User A is then allowed to send out the draft quote/ invoice and vice versa. User should be not allowed to approve quote/invoice that he/she has drafted.

Hi Madeleine, thanks for sharing your idea around having an approval process for both quotes and invoices. It's something we've seen come up from time to time, and it's helpful to understand how it fits into different workflows.
Just to clarify, invoice approval is already achievable in Xero and can be set up by adjusting user roles and permissions. This allows you to manage who can create, approve, and send invoices.
For quotes, there’s already an existing idea for quote approval that was raised by another customer. We’ve added your vote to that idea so it’s included in our tracking, and you’ll be notified of any updates.
If there’s any extra context you’d like to add, feel free to comment on the idea directly, that kind of insight is always useful for the team.
You can edit your post, and respond directly to my update if you'd like us to re-review.