I just run teleporter on my primary and manually upload that backup to my secondary. My blocklists and local DNS dont change much, so its not a big concern of mine.

Nebula-Sync and Orbital-Sync may be of interest to you. It seems like you want to automate the syncing.

I’ve been running DietPi for years. Its so lightweight and stable. I love GUI-less Debian and its chefs kiss on a Raspberry Pi.