Very much agree, having kids has totally changed the way I work. I definitely have less time to do side projects and have to heavily coordinate with my wife when I want to work on a side project.
On the other hand I have had the experience that I am much more focused when I have the time as it has become more precious in a way. My motivation to create something new that could potentially benefit my children is also much higher. Just have to be careful not to convert motivation to self-pressure. It can be a thin line sometimes.
I think there is really something to the idea that as time becomes more precious, you use it more productively. It reminds me in a way of the idea that constraints, for example in art, are where true creativity comes from. Having absolutely no boundaries at all isn't actually a recipe for great artistic expression. It's a loose analogy, but in somewhat the same manner, when you feel absolutely no limitations or demands on your time, you simply squander it. I think someone once said that if you really want something done, find the busiest person you know and ask them to do it. As counterintuitive as this seems, it's very true in my personal experience. People who are busy and who have a lot of demands on their time are quicker to stop starting and start finishing.
On the other hand I have had the experience that I am much more focused when I have the time as it has become more precious in a way. My motivation to create something new that could potentially benefit my children is also much higher. Just have to be careful not to convert motivation to self-pressure. It can be a thin line sometimes.