If there are 2 items in the cart and one is eligible for Express delivery & Standard and the other only Standard, Can the shopper be able to choose express for first item and Standard for second?
Unfortunately not. The VTEX Checkout will always work to reduce the number of deliveries for a given order, so if two items share a delivery method that method will be selected for both.
The only way to split deliveries would be if they do not have any shipping methods in common.
Field Software Engineer | VTEX