Maybe the above is an European thing.
I don't even remember (been a while since I did lots of interviews) if you're allowed or not allowed to ask any of the aforementioned things but I can tell you from experience that about half the candidates would mention their partner and/or kids anyway, because it just is usually not a problem. But it's not such standard fare that someone not mentioning would raise a flag either. I guess most of us just don't think about it.
Also, tech is a bit different and I am not that old - but in Germany you could see a ton of personal details absolutely no one is interested in on CVs, but it's getting better. (What your parents do for work, if you are married, what name you had before marrying, if you have a driver's license for a desk job, what primary school you went to, etc.pp)
It's totally something you can bring up later, when already hired, if the job description made clear that it gives you flexible working hours.
That said, I have been asked if I had kids, in an interview. Later in my career, when I was trained to perform interviews, I was explicitly told to NEEEEEVER ask that. And if the candidate volunteers it, to basically pretend you didn't hear it.