This is a small plugin for generating PDF files from the WooCommerce Admin Shop Order page
The plugin is using a super service which helps generating PDFs via API. https://www.html2pdfrocket.com/ They have a free tier to 200 credits and then affordable plans.
Just change the $apikey to your API key and start using this plugin.
The plugin is in Hungarian language, but if you know HTML you can change it to you liking.
The Warranty List uses a free invoice template: https://github.com/sparksuite/simple-html-invoice-template