Anytype has finally followed through on their promise and open sourced their repositories. Self hosting is now possible though there is no docker container available.
This is a major step forward for all PKMS and I wholeheartedly congratulate them.
btw Anytype is free, even their included sync service, which is the best of any offline-first style PKMS I have experienced. Anytype is top 3 PKMS for me, followed by Logseq and SiYuan. They're in good company and now it's only going to improve!
Just to clarify the entire Logseq app is open source including the sync mechanism, the server backend to receive the sync endpoint and store the data isn't.
I use Syncthing (FOSS and cross platform) to sync noted between my devices.
I couldn't find a good one on their site so I downloaded the app. It's a fancy notes app with templates for a bunch of different things. The hook seems to be the decentralized sync system.