OP @PurpleChevron I don't want to be presumptuous, but could it be a possibility that you are or are beginning to get depression??
From what you write it sounds like it could be a possibility but I'm no doctor.
I think most people are struggling a lot with this whole thing, in different ways. It's completely normal that you are feeling this way even if it's not your 'normal' normal iyswim??
I recognise the absence of any motivation, wading through treacle feeling trying to do the slightest thing, and brain fog.
Things which maybe, possibly could help -
Speak to GP. I thought I'd be wasting their time and resisted for weeks but they were great.
Divide things into manageable chunks. Either one or two to-dos at a time then break, or say 30 mins doing stuff 30 mins break.
Promise yourself a treat after you've completed tasks. A film, chocolate, whatever you usually like.
Strike whilst the iron is hot. If you feel a rare sudden motivation, go with it.
Delegate. Depending on ages, Children can help out.
Vent to trusted Family and Friends. Mine have surprised me how much support they've given.
Don't know if this will help but I'm the same, was much much worse before getting help from GP (which I've never needed before), and these help me.
Hope you feel better soon..