Don't some DNS servers implement something that acts like a server-resolved CNAME, where the admin puts in a record that points to some other DNS name but the client just sees an A (out AAAA) record?
Yup. some implementations provide similar ANAME, and Cloudflare has flattened CNAME which is probably the best implementation I came across in years of supporting folks trying to use these kinds of records on a large CDN.
