Been using Syncthing with graphs forever now. Probably will continue using that.
I haven't followed Logseq much since they announced the move to a database. I liked the idea when it was a regular open source project. They've taken a considerable amount of money from outside, they're moving from plain text files to a database, and they're planning to monetize by selling sync features.
We've been down this road, I don't know, maybe a few thousand times before. We know how this story ends. Heck, we could write the blog posts and the defensive comments about sustainability, running a business, and all that jazz right now.
(This comment is not a request for a lecture on how business models work. I understand how they work, and that's the point of my comment.)
I wonder if a database is required for CRDTs. I don't know if logseq use that, but if we had a FOSS note-taking app with CRDTs, we might have to give up the text format.
If you want to preserve the ability to edit plain text files using an arbitrary program, your sync engine could be a file watcher that computes a diff each time the file is saved - like git does, but character-based instead of line-based.