produces usable output to build a progress indicator on it
Probably not since you can't tell in advance how much output will be created, but you could stream that output to a text window to give the user something to watch while the DB is being built.

Since the DB dump is just an ASCII file, you could scan it in advance and count the number of certain key commands (like CREATE TABLE) and use that to set the upper limit for a progress indicator. If the MySQL progress report shows the command it is executing, then you could look for the same command to appear in stdout and bump the progress indicator each time.