Configuring multiple v4 addresses on an interface is a kludge, typically only used on hosts which apply inter-network routing logic. It’s an explicit, primary function of the standard v6 specifications.

With v4, you would use either RFC1918 and NAT, or plumb a public address to the host.

With v6 you should use a ULA and an address with a public prefix, and selectively open ports/services to on appropriate address.

An example is the file sharing and administration daemons on my NAS are only bound to its ULA. I don’t need to worry whether it will accidentally be exposed publicly through fat fingering my firewall config, because it will never route beyond my gateway.