I use syncthing to sync form Mac OS to Linux. Because extended attributes get lost I made my Mac “Folder Master” with the hope that some day extended attributes will make it to the other side for changes to go in any direction. Of-course Linux supports xattr as well, so the reverse problem may apply in other cases. So far this is not a critical issue for me, though I use tags a lot. This helps me keep a flatter, more manageable directory structure.
Because I use color tags a lot, I’m hoping that an eventual solution will allow to blacklist (or else whitelist) certain tags for a partial tags sync. That however is not as important as preserving the tags to begin with.
Keeping metadata as part of the filesystem is imo superior to non-standard solutions. So I’m considering something silly like implementing this filesharing idea with extended attributes. An alternative would be to use cozy cloud or something. With cozy though the files are in couchdb which is less convenient than straight fs.