Sync files offline?

Question

linux

There is a remote (offline, no internet, no lan, there is usb, you can turn on flash drives, Ubuntu) computer No. 1
There is a second computer No. 2 working on the network (Ubuntu). having the Internet (but it does not matter).
There is a directory on both computers (large enough) that I would like to synchronize with each other.
User case No. 1:
Information in the catalog changes on computer No. 1, after a while a person comes with a flash drive and transfers the changes to it.
He comes to computer #2, inserts a flash drive - the catalog is synchronized, the changes are written from the flash drive to computer #2.
User case #2:
Information in the catalog changes on computer #2, after some time the changes are dumped onto the flash drive, and the person goes to computer #1, where the catalog is synchronized.
We believe that there are no file conflicts (let's say this - we indicate that remote computer No. 1 has a higher priority.
Files usually do not change, i.e. they can be deleted, moved, created, but if it is possible to track file changes, then buzz.
USB flash drive should be only an intermediate link, there should not be a copy of the directory on the flash drive (the whole thing will not fit in.
Are there any ready-made solutions?
All sorts of Git, Diff, etc. come to mind, but the directory size is quite large, about 300 GB, binary.

Answer 1

rsync

Answer 2

Probably I would do this to
save the last date_time of synchronization somewhere, when synchronizing, I would copy files to the USB flash drive whose date_time of the last change is newer, and, accordingly, have priority A over my files, priority B for the flash drive.