I happen to have kids and have always spent about 30 min a day, more like an hour, every day, looking at some side coding side projects. Being doing that before I was dad, now less since I am. But I still do. I'm past 50 now and I must admit the quantity of work I put out on side projects have decreased.
Side projects requires passion, not discipline, not effort, just passion. And that's what I'm looking for. When you like what you do you're generally good a it.
Now, I have hired people who don't have side projects, of course, they're not that common but not rare neither. And the side project question is sure not the main question. But that's a cool differentiator.
Moreover, questioning people on their side project is always more fun for them.
And of course, people with side project sometimes day dream so you have to keep them busy :-)
And having a github repo is a 15 minutes job. And most of the time, nobody will care about your side project. It's not like your marketing yourself. As I have said, I don't care about the stars. Just looking at what you do on the side, what interests you in a domain that is not far away from your job.
And side projects are always cool: I have interviewed people who were working on their game engine, planet trajectories, web sites for friends, playing with machine learning, writing little tools like Javadoc,...