GnuBee is a personal NAS (Network Attached Storage) cloud server that is currently being funded on Crowd Supply. It is a low-cost, low-power, NAS device that runs GNU/Linux and it is claimed to be based on free, libre, and open source software. No proprietary drivers needed to use GnuBee.
Little Snitch is a traditional software firewall for macOS. You can use it to monitor applications, preventing or permitting them to connect to attached networks through advanced rules. OpenSnitch is a GNU/Linux port of the Little Snitch application firewall written in Python.