In the network settings of home assistant OS there are 3 configuration options for IPv6, Automatic, Static and off. when running a network without DHCPv6(for reasons) this makes letting severs have shorter addresses a little more annoying.
Linux does support a Draft RFC for a user configured host token, so that it still gets prefixes from a RA, but it can have a manually assigned host segment.
Under NetworkManager this is configured using
which would combine with a prefix of
2001:db80:2894::/32 to become