Create an S3 bucket in each AWS account for the artifacts. Allow the pipeline to write to the S3 buckets. Create a CodePipeline S3 action to copy the artifacts to the S3 bucket in each AWS account. Update the CloudFormation actions to reference the artifacts S3 bucket in the production account.

Create a customer managed KMS key. Configure the KMS key policy to allow the IAM roles used by the CloudFormation action to perform decrypt operations. Modify the pipeline to use the customer managed KMS key to encrypt artifacts.

Create an AWS managed KMS key. Configure the KMS key policy to allow the development account and the production account to perform decrypt operations. Modify the pipeline to use the KMS key to encrypt artifacts.

In the development account and in the production account, create an IAM role for CodePipeline. Configure the roles with permissions to perform CloudFormation operations and with permissions to retrieve and decrypt objects from the artifacts S3 bucket. In the CodePipeline account, configure the CodePipeline CloudFormation action to use the roles.

In the development account and in the production account, create an IAM role for CodePipeline. Configure the roles with permissions to perform CloudFormation operations and with permissions to retrieve and decrypt objects from the artifacts S3 bucket. In the CodePipeline account, modify the artifacts S3 bucket policy to allow the roles access. Configure the CodePipeline CloudFormation action to use the roles.