Bump on this. ALB support would be most excellent.
Related: Is this add-on developed open source? If so, I'd absolutely take a shot at a PR for it but I'm guessing since I haven't found a link to github yet, it's not public.
edit: Found a github project but it's either the same project before it became internal to splunk or it's unmaintained and/or not the same project: https://github.com/splunk-apps/splunk-aws-addon