OP, you have my complete sympathy. Firstly, your children have you, and you love them. This is already worth a huge amount on it's own.
I have 4 sons (8, 6, 4 and just turned 2). We just returned to school this week after 10 weeks of homeschool (locked down after October holidays). We live in Slovenia.
DH was busy most days trying to find ways to keep his business going.
I (barely) coped by having a fairly rigid routine and letting go of any expectation of doing anything except dealing with the children.
We got up around 8, had breakfast, got dressed and brushed teeth. The 6 year old's zoom call began at 9, 3 mornings a week and lasted about 50 minutes. The 8 year old's zoom call began at 9.25 every day and lasted just over an hour.
So, at 9am I put cartoons on in our bedroom for the 2 littlest ones and settled the 6 year old at the laptop in the kitchen. 8 year old in the childrens' bedroom, we checked he had everything ready for his call, then he went in on the tablet.
Then I checked on the little ones. Then tidied the kitchen while checking on the 6 year old. When his call finished I sat down and did half an hour of his tasks with him. If it was a day where he didn't have a call we did an hour. That was enough to complete what he had to do.
Then when the 8 year old finished his zoom call I brought him down to the kitchen. 6 year joined the 2 youngest in front of the TV (with snacks) and I would do an hour of work with the 8 year old in the kitchen, whilst preparing a packed lunch.
Then, around 11.30- 12 we all went out, regardless of the weather. Youngest had a nap in the buggy and we went for a walk with a picnic lunch, stayed out til around 3 or 4. DH made tea. Then free time, they mostly played with Lego or sometimes we put on a movie. Bedtime routine from 7, little ones to bed at 7.30, older ones at 8 or 8.30 after stories.
It was monotonous and I had issues getting them out of the house most days. And felt very bad about how many hours of TV time the younger ones were clocking up. We cut corners on the school work. I insisted that they kept up with maths, reading and writing but didn't sweat every single task beyond that.
To be honest, getting outdoor excercise every day, eating sensibly and trying to promote their friendships with each other were my main priorities. I didn't want them to fall behind at their schoolwork, but more because I didn't want them to have issues when they went back to school. I don't personally think the actual work matters all that much at this age.