List available AWS RDS instance type with go SDK

Question

I'm trying to list all the available instance types that I can spawn for a given DB engine (Postgres/MySQL). This at the moment is possible using the AWS CLI with the following command:

aws rds describe-orderable-db-instance-options --engine mysql

more options can be seen on this docs page - describe-orderable-db-instance-options

However, when I try to achieve the same with the aws go-sdk I can't find any similar function that can give me the list of available instances. Docs can be referred here - https://pkg.go.dev/github.com/aws/aws-sdk-go/service/rds

I am NOT interested in trying to list the provisioned instance and examine their instance types. Instead, this is supposed to be a pre-provisioning step that allows me to choose available instance types.