How can I programmatically determine which instance types support IO2 block express without scraping support pages?

Hi, Yes, you're right: DescribeInstanceTypes does not allow exactly what you are looking for but helps you finding some hints toward our questions with some of its filters:

See https://docs.aws.amazon.com/cli/latest/reference/ec2/describe-instance-types.html

ebs-info.ebs-optimized-info.baseline-bandwidth-in-mbps - The baseline bandwidth performance for an EBS-optimized instance type, in Mbps.
ebs-info.ebs-optimized-info.baseline-iops - The baseline input/output storage operations per second for an EBS-optimized instance type.
ebs-info.ebs-optimized-info.baseline-throughput-in-mbps - The baseline throughput performance for an EBS-optimized instance type, in MB/s.
ebs-info.ebs-optimized-info.maximum-bandwidth-in-mbps - The maximum bandwidth performance for an EBS-optimized instance type, in Mbps.
ebs-info.ebs-optimized-info.maximum-iops - The maximum input/output storage operations per second for an EBS-optimized instance type.
ebs-info.ebs-optimized-info.maximum-throughput-in-mbps - The maximum throughput performance for an EBS-optimized instance type, in MB/s.
ebs-info.ebs-optimized-support - Indicates whether the instance type is EBS-optimized (supported | unsupported | default ).
ebs-info.encryption-support - Indicates whether EBS encryption is supported (supported | unsupported ).
ebs-info.nvme-support - Indicates whether non-volatile memory express (NVMe) is supported for EBS volumes (required | supported | unsupported ).

Max iops and max throughput help in defining if IO2 block express is supported by a given instance type based on the perf of IO2 itself.

Best,

Didier