I use Joplin. They have a sync server you can host for yourself.

Best I remember from the doc I watched, TempleOS doesn’t even have a network stack.

Technically even the time we did it only officially after the fascists declared war on us first. It was all lend lease, etc before that.

I use 2 matching Synology NAS systems. 1 backs up to the other daily. Then one of them backs up to Synology C2 weekly.