> people who work on interesting side projects. If your side project is boring, that will probably bore your interviewers -> no offer
This hasn't been my experience at all. The interviewer doesn't care how "interesting" the side project is. What they want to see is what your actual working code is like, that you demonstrate a good grasp of programming concepts, etc.
I wouldn't be worried about boring my interviewer and getting rejected because they consciously recognized that they were bored, I'd be worried about there not being a level playing field between projects when the hiring committee is discussing it later. The guy who built the fun video game will probably be remembered more fondly than the guy who built the CLI tool for tracking the weather.
This hasn't been my experience at all. The interviewer doesn't care how "interesting" the side project is. What they want to see is what your actual working code is like, that you demonstrate a good grasp of programming concepts, etc.