Quite often, my wife was working upstairs, I downstairs, my oldest son in his room, and my youngest son was mostly playing and watching TV with the occasional school-related lesson on a tablet. On Thursdays, our cleaner would come, and we all had to cram into half the house while she cleaned the other half, or we had to leave the house. Sometimes we ended up working in bed or on the balcony.
My oldest son was quite capable of doing his own schoolwork, though he's always finished way too quickly and spent the rest of the day gaming, so this made his gaming addiction a lot worse in retrospect, but at the time, he didn't need much attention. Or youngest did, though. It's hard to work when a 5-year-old wants your attention. But our regular babysitter had all her other babysitting jobs and restaurant jobs cancelled, so eventually we hired her 3 days a week to entertain and teach our youngest, and that worked very well. I still ended up shifting a lot of work to the evenings and weekends, which works fine: play with your kids during the day, work in the evening. There's not much else to do anyway.
So the isolation wasn't perfect because of outside help, but that did make it bearable. We always kept a lot of distance from our cleaner (who always wore masks and gloves), and the babysitter didn't have much else going on in her life anymore, so we figured she wasn't a big risk.
So I guess that's my advice: adopt a near-permanent babysitter. There are probably plenty who are currently our of a job, and as long as they don't do much else than babysit at your place and go back to their own home, they're not a big risk. Get someone responsible, though; not a party animal.