I do believe the AWS Load Balancer Controller on Kubernetes allows for sharing a single "physical" load balancer.
You have to set a load-balancer-name annotation https://kubernetes-sigs.github.io/aws-load-balancer-controll... to tie everything together to one load balancer. There is a downside where you have to have a few other annotations be the same value across your ingresses, but once you work around that, you're good to go.