Something like the ASRock J3455-ITX will do the job. 10 watt quad core, though my beef with this board is it features an m.2 B key wifi slot instead of an M key

Something like the ASRock J3455-ITX will do the job. 10 watt quad core, though my beef with this board is it features an m.2 B key wifi slot instead of an M key for an NVMe storage device which is a poor choice. There might be a better board out there with a similar low power celeron. I have an older asrock j1900 celeron board running my 9front CPU/Disk/Auth server at home 24/7. No issues and it has been solid. At the current electric rate it costs about $2/month.