Create a customer-managed prefix list. Add entries for the initial list of on-premises IPv4 hosts. Use AWS Firewall Manager to share the managed prefix list with the organization.

Create a security group. Add inbound rule entries for the initial list of on-premises IPv4 hosts. Create a resource share in AWS Resource Access Manager. Add the security group to the resource share. Share the resource with the organization.

Create an Amazon DynamoDB table. Add entries for the initial list of on-premises IPv4 hosts. Create an AWS Lambda function that assumes a role in each AWS account in the organization to authorize inbound rules on security groups based on entries from the DynamoDB table.