I'm sorry but jealousy is natural and I am jealous when my Christmas is two snotty, needy children following me around as I try to take washing upstairs or do the washing up. I do wish I had a couple of hours free to fold washing or sort socks whilst catching up on Call the Midwife or bake off. I'm in my twenties so most of friends don't have children or have partners who don't have to go back to work on Boxing Day. I am jealous. I know they have things to do and time spent seeing family as well but I just want a break. I'm not apologising for that.
I'm not trying to make light of your position, OP, but I think this is a very valid point you're making.
Having babies is hard. It's a thankless, miserable task. They are not cute, chuckling bundles of joy. This is the reality of it. I'm not denying there is joy to be found, of course not, but this is the bulk of it.
And I also think that if this view of it were presented more often, and people were more honest about the realities, then there wouldn't be 20 somethings with 2 children, 2 and under, with 'absent' partners because women would 'get it' long before they experienced it for themselves.
Extra Just ask someone. Like I said, I wouldn't volunteer. I wouldn't give up my free time willingly, I would worry that if I said to someone "can I take the children for you and give you an hour?" that they might infer an implied criticism and, tbh, it just probably wouldn't occur to me.
But if you asked, and I were able, then I would take them.