Sync principle and logics in linux env

Will sync work when several linux devices all running brave is on the same “sync code” and some device are shut down and some not and the devices are not on the same network or location. And in this set of devices som of them are upgraded with following need to sync up again…
So, with a linux-env. like above:
=> If sync can not find a sync’able device what does it say then.
=> Why does it complain when I try to sync FROM a previous upgraded device with new sync chain and code on to a LATER upgraded device.
=> Is this sync function perhaps to complex if it is based on “only” locally stored data. Perhaps, it is more simple just to export the html bookmarks file and put it on the USB…and then on the upgraded device
=> Is this “sync” logics/principle correct described?
=> I changed from Chrome to Brave for other reason than sync. But Chrome has cloud based sync and it was very easy to use.

I may have missed something…