You can’t design for every eventuality in advance, but, for proper contingency planning, you should develop an understanding of the kinds of things that can go wrong and of your users’ main concerns, and find the best way to clearly explain limiting circumstances and plan your response to fast-changing constraints.

Read the entire Nielsen Norman Group article which has many insights for all kinds of online purchases: Online Shopping for Food and Groceries During Covid-19: Workflow Issues Impact the Ecommerce Customer Experience