How can I add attribute values to orders using Shopify-buy SDK?

Hi there

Does anyone know how to add attribute values to orders made through/with shopify-buy?

I am trying to build a store with Gatsby using the package called gatsby-source-shopify(https://www.gatsbyjs.com/plugins/gatsby-source-shopify/) and also trying to add an input space where customers can add extra info (such as delivery date and time or name on receipts etc)

I haven’t been able to figure out how to do it so if anyone knows how to do it or docs which explain the way, that would be very appreciated.

thank you!!