It really seems like there should be some kind of "SyncGUI" app built into Linux that does this sync with a nice GUI, and maybe there is one, I've never looked

It really seems like there should be some kind of "SyncGUI" app built into Linux that does this sync with a nice GUI, and maybe there is one, I've never looked that up... because all it needs to do is prompt for source and destination folders, with a stern warning about what it DOES. ha.