I'm coming from the 8 hours sleep, 8 hours of work, 8 hours of other stuff. There will obviously be things like chores and eating in there, but I think there is meaning and purpose derived from those things as well.
It takes me two hours from waking up to walking into work, so now we are at 6 hours. Then it takes me an hour to get home, down to 5. After prepping, cooking, eating, and cleaning dinner, as well as making lunch for the next day (usually just packaging leftovers), I lose another hour at least, 4 hours left. Getting ready for bed is a whole process, and the average human takes 14 minutes to fall asleep, so call it a half hour there, and throw in a half hour for just misc. waste time throughout the whole day for good measure, and you are left with three hours, or 12.5% of your day, that is truly yours. If you need to run an errand after work or do some chores, that time evaporates.
I guess you can strive to make productive use of those 180 minutes, but after a whole day it's hard to work remotely efficiently. A quick peek on HN turns into a 30 minute stint. I love playing guitar and reading books, both make me quite happy, but I find sometimes there just isn't enough time to engage in these hobbies, which makes me depressed. Sometimes I indulge on the dopamine hit of playing guitar for an hour or two, which makes me very happy, but at the cost of sleep, which ruins productivity and energy the next day, I get less done, and fall to a new low.
Sometimes I wonder how older generations of my family coped with full time factory work half a century ago, then I remember all of the raging alcoholics and realized that no, they didn't really cope well with this post industrial revolution work week construct either.
Transportation and meals come from that "other stuff" bucket, at least for 90% of jobs out there. You work for 8 hours and hopefully sleep for the full 8 hours. The edge cases all get taken out of your "free time" and what is left over is the time you get to spend on you. Which is way, way less than 8 hours.
I would say it's closer to 4 hours max. With kids, zero. It's hard to find meaning in those 4 hours when life is so complex. I would even argue that you need a dedicated entertainment bucket just to stay sane which further limits this other stuff bucket to merely a large handful of minutes. This handful of minutes is where you live your real life and it's really not enough.
How many hours are in your day? I don't even have kids and I don't even have 4 hours in a workday doing things I actually like to do.