Redshift-Managed Endpoint

Yes, you can achieve this connection using a Redshift-managed VPC endpoint. This approach allows for secure access to your Redshift cluster in a private subnet from a different AWS account. Here's how you can set it up:

1. As the owner of the Redshift cluster, you need to grant access authorization to the client's AWS account. You'll specify their AWS account ID and VPC identifier (or all VPCs) when granting this permission.

2. Once you've granted access, the client (grantee) account will be notified that they have permission to create a Redshift-managed VPC endpoint.

3. The client can then create a Redshift-managed VPC endpoint in their VPC. This endpoint will provide a private connection to your Redshift cluster without requiring public internet access.

4. After creating the endpoint, the client can use it to access your Redshift cluster securely.

It's important to note that when using Redshift-managed VPC endpoints:

• Your Redshift cluster must use the RA3 node type for provisioned clusters.
• You need to ensure that your cluster is available within valid port ranges.
• You should manage VPC security groups and quotas appropriately.
• The Redshift-managed VPC endpoint is not accessible from the internet and can't be managed using the Amazon VPC console.

By following this approach, your Qlik-SaaS client can securely connect to your Redshift cluster in a private subnet, even though they're in a different AWS account. This method provides a private and secure connection without exposing your cluster to the public internet.
Sources
Redshift-managed VPC endpoints - Amazon Redshift
Access Redshift in cross region setup using VPC endpoint and VPC Peering | AWS re:Post