For anyone searching for a solution to skip the unchanged files and show only the modified/deleted/added files, the best option is to remove the lines that start with unchanged from the output with sed by piping the output of restic to it:
restic backup | sed '/^unchanged/d'
I created a backup.sh that contains this code so I can easily run it without typing over and over.
The benefit of this approach is that the output is live, line after line, but the lines with the unchanged files are simply skipped.