There is a new pull request by ahesford against master on the void-packages repository

https://github.com/ahesford/void-packages runit-nftables
https://github.com/void-linux/void-packages/pull/18480

New package: runit-nftables-20200123
This package is analogous to runit-iptables, loading existing rules at /etc/nftables.conf (the file expected by the service installed by the nftables package) on boot.

A patch file from https://github.com/void-linux/void-packages/pull/18480.patch is attached