is there a progress bar for iCloud sync'ing?

Kind of, but it depends on what you're syncing and where you're looking.

In Finder on a Mac, You'll see a circle (with a pie wedge that fills as items are uploaded) next to iCloud. You can also click the "info" icon to see the progress.

In something like Photos. Go to library and scroll to the bottom. You'll find the current cloud status.