it was ultimately pretty easy, since im  with netifrc going, i was finally pointed to by someone in the #gentoo irc to the default config examples for /etc/conf.d/net and with some followup i found out that i just had to symlink the service file for the ens18 device, and then do this:

config_ens18="dhcp 2605:a141:2219:1995::1/64"

(its not exactly a secret, this server is broadcasting an ip address thats kind of the point here lol) and i was able to restart the interface without it kicking me out of the ssh yay! anyway just some #akkoadmin #fediadmin #contabo #gentoo #netifrc #ipv6 tips as i did not find any of the documentation on this straightforward, especially since netifrc isn’t as in vogue as whatever systemd-based hunks of junk everyone is running now