Yup. With young kids and a spouse you're lucky if you get 15 hours of actual solo free time a week, unless you're cutting into sleep. And they'll be scattered throughout the week, then further broken into smaller parts by various interruptions, some probably claimed by various family & friend events more weeks than not unless you don't... you know, do stuff with people.

If you want to have side projects under those circumstances, I hope you like working in chunks of a few minutes at a time, days-long gaps in between sessions, with the constant threat of interruption looming and an ever-growing pile of things-you-should-probably-be-doing-instead stressing you out.