Replace the existing ALB with a Network Load Balancer (NLB) and assign an Elastic IP address to the NLB.

Allocate an Elastic IP address and associate it with the ALB, then provide this IP address to the customers.

Deploy an AWS Global Accelerator standard accelerator, configure it to use the ALB as its endpoint, and furnish the accelerator's IP addresses to the customers.

Set up an Amazon CloudFront distribution with the ALB as its origin, determine the distribution's public IP address through its DNS name, and supply this IP address to the customers.