On a personal note if it's of any use to anyone else I let go of the idea of ds needing to do his school work synchronously or to do everything. As a parent all live lessons would be a nightmare for this household - those who did them recorded them thankfully.
There are weekends and evenings (thankfully as he quickly went semi nocturnal). You can also make executive decisions such as focusing on core subjects/areas and emailing the school to let them know you won't be doing x, y or z because you can't cope with all of that and are prioritising a, b and c. I did this for sure.
It doesn't have to be done full on from 9-4 or whatever. You can sit down and look at what's there, decide what they can do independently and say right I'm expecting you to get English, History and Business Studies done by 12 and then you can do what you want BUT we'll have to sit down and do Maths this evening after dinner together (if eg Maths is problematic for them) and you can decide fuck it that lesson from eg. D&T looks stupidly complicated and pointless so we'll write that off.
Some would disagree with me but that's the kind of thing I had to do to deal with being a single parent in a demanding job and having a seriously unmotivated son who is definitely not a self starter school work wise.
Re-arranging is my point as I said. Of course it's a nightmare for all of us and we have to do the best we can in our own circumstances as a parent. As a teacher I had my laptop on all of the time and would answer email questions as they came through at 9pm at night and be recording lessons at 6am when the house was quiet and I'd be uninterrupted. The whole 9-5 thing went out the window and clearly not all of my students were working to those hours either if I'm getting emails and queries in the late evening.
Also bear in mind that an hours lesson at my school includes movement time, getting sat down and settled and books given out and equipment unpacked, packing away time, a bit of chatter and discussion etc. For my remote lessons I aimed at about 20 minutes of recorded teacher input and video clips etc and 25minutes -however long the really diligent ones wanted to spend on it worth of independent tasks. My lessons were all recorded and then I'd sit in a google meet room at the synchronous time of that lesson in case anyone from that class wanted to ask me anything or just have a chat by joining the meet.
Hopefully we don't go down this road again and we turn out to be able to manage to keep things open (my GP is already closed to all but emergencies and vaccines though) but if not it will be ok. Try not to doom and gloom yourself into a self fulfilling nightmare and rejig things to work for you and your household and feel free to make executive decisions about priorities. Eg. If your child is not taking drama/Geography/whatever next year due to options and there isn't time to do everything then only do the subjects they'll be taking. Or if your child is great at reading and capital letters and full stops already, or whatever the focus is from school, feel free to do some reading and verbal comprehension questioning together in bed that night instead of the literacy lesson.
Sorry if this is all completely unhelpful.