You can also serve the cache directly from the local Nix store on NixOS. This is useful if you are self-hosting the cache on the same machine that builds it. I do this for my home-server, which is relatively powerful compared to my ultrabook, and so I do most builds on it, which automatically gives me free cache, without having to manually push.

• First, switch to NixOS as your distro
• Then serve the local nix store as cache using https://nixos.wiki/wiki/Binary_Cache
• If your computer is in your home, you can use Wireguard (all configured declaratively in nix) to expose it: https://twitter.com/sridca/status/1308808239677571072

The linked tweet contains links to my Nix configuration.

Somewhat related: https://blog.ipfs.io/2020-09-08-nix-ipfs-milestone-1/