This was posted a few months ago: it's a less structured solution, but it's super simple, free and code is available: https://invoicedragon.com/
Why not use excel/google sheets?
(Wont mention libreoffice until their UX for their powerpoint has the text size on the main screen. They have some FOSS saboteur on the team of something)
My invoices still use the Office 97 template I started with.