My vendors find woocommerce variations very difficult to understand.
Woocommerce Product AddOns are much more simple.
Dokan have this integrated so vendors can add product addons to products:
https://snipboard.io/eJZX76.jpg
https://snipboard.io/IwFxjX.jpg

and they can also add global ones to automatically get added to specific categories or all products to make the process less time consuming:
https://snipboard.io/0YgnMU.jpg