FT-Sync, unofficial utility to sync Freetube data
ft-sync
Linux only (I think), only between desktop clients, and it requires a server.
In the short time I've tested it, everything worked.
This sounds amazing! Hopefully they're able to support Android clients soon.
I have it set up on 3 computers and can now report that it works really well. No waiting for it to sync, it's all right there when opening Freetube. I had been hoping for something like this for a while.
Android would be great indeed.