11yo boy at home alone all day?

[warrior2018]

My ex and I are mid divorce and during discussions about childcare over the summer holidays he told me he would be working a certain day he normally has them and asked if I could - I’m working too - he then told me he’d be happy for our eldest (11 yo boy) to be “pottering around at home”. This means leaving him alone from when he goes to work at 08:30am until he returns at 6:30pm.. longer if he gets held up at work. I am totally against this. He has already given 11yo a set of house keys to his house and leaves him alone for around 3 hours after school until he gets back from work some days which I was not totally in favour of but now I’m worried he’s being left alone at home for longer periods alone. AIBU to think that’s not on?! 11yo has a phone but still..

What does your son think about it? Does he have any friends within walking/biking distance so he could be home alone in the mornings then go see friends in the afternoons perhaps?
It would be completely normal for an 11 year old to be home all day alone in the holidays where I am, there's no holiday childcare for children over 7 in my town at all so even my 8 year old has to be home alone-ish (big sister home but she sleeps all day) so it is of course doable but better if he can spend time with friends rather than be all alone.

An hour max. Longer than that really isn’t fair.