On Demand Capacity Reservation: minimum duration?

Hello.

I think it's probably explained in this document.
https://aws.amazon.com/ec2/pricing/on-demand/?nc1=h_ls

On-Demand Instances let you pay for compute capacity by the hour or second (minimum of 60 seconds) with no long-term commitments. This frees you from the costs and complexities of planning, purchasing, and maintaining hardware and transforms what are commonly large fixed costs into much smaller variable costs.

It is also mentioned in this document.
https://repost.aws/knowledge-center/ec2-instance-hour-billing

Your Amazon EC2 usage is calculated by either the hour or the second based on the size of the instance, operating system, and the AWS Region where the instances are launched. Pricing is per instance-hour consumed for each instance, from the time an instance is launched until it's terminated or stopped.