The OpenWrt odhcpd is a minimal dhcpv4 and dhcpv6 router that is easy to configure.
(I needed something that just works, while dhcpv6 is getting implemented in the great rust dhcp server dora)
This flake builds odhcpd against the master branch and not against a fixed release, so you are sure to be up to date.
I had to move fast and couldn't wait for a nix package to be merged to unstable. But don't worry the code base is so ridiculously small that building from source happens in a blink.
Of course there is a module that starts the required systemd units.