It shows that you care enough about electronics to work on it in your own time.
To a smart employer that means you are keen, likely more generally knowledgeable than someone who doesn't, and they don't have to pay money to keep your still up, as you are already doing it yourself.
People who have an active interest in electronics outside of work generally make better engineers, for all sort of little reasons.
That's why the project itself doesn't matter, it's just the fact that you had the motivation to do it in the first place.
Dave.