Well done article! Just one observation:
The domain struct for Account is mixed with the repository and it’s tightly coupled with an infrastructure component (Field of type DynamoService por Account struct). As a solution of this, I would create a Repository interface and another struct called “AccountRepository” that implements the interface and that make all the work with the database. With this, the domain of the application will be just the structs with no relation to infrastructure or database.
Keep going! the rest of the article it’s very clear and helped me a lot to understand about the implementation of the architecture in Golang.