I’m not in the market, but I’ve actually had similar thoughts of building a project on top of NixOS that’s focused on self-hosting for homes and small businesses. I recently deployed my own router/server on a BeeLink mini PC and instead of using something like OpenWRT, I used NixOS, systemd-networkd, nftables, etc.
DM me if you want to discuss more. I think the idea has potential and I might be interested in helping if you can get the business model right (even if it just ends up being some FOSS thing).