Optional extra warranty payment implementation

Hello,

We are interested to implement an optional extra warranty payment for order items. The user can decide if he/she wants to pay some extra fee for a specific product at in check-out stage, in order to get some extra warranty. Is there anything similar implemented in the project that we can use?

Thank you.

I'm thinking about checkout attributes but they have cart rather than cart item context. See Catalog > Checkout attributes in backend.