Hi @kattlegaspi!
Adding a variable product description in the invoice isn’t a core feature of WooCommerce.
To achieve that, you would need to use a plugin or some custom coding.
In the case you want to make a customization to your invoice or any WooCommerce feature, I recommend getting in touch with one of the customization experts listed on the WooCommerce Customizations Page.
Or if you are into coding, you can also visit the WooCommerce Facebook group or the #developers
channel of the WooCommerce Community Slack. We are lucky to have a great community of open-source developers for WooCommerce, and many of our developers hang out there, as well.
I hope this helps!