It's worth keeping at in mind that people are currently unable to use the advantages of working from home to replace lost camaraderie because of the virus. At the very least, it's much harder to do so. This is important for the broader effects on human happiness, if not on the effects on work itself. Once socializing in person isn't dangerous, people can use the hours of the day they save from not commuting, plus all the time they spend in neutral social interactions in the office (which are net negative because they take energy and time ...
Give it to an existing EA group or groups doing good work, like Givewell. They probably can't absorb $1bn immediately but they could use tens of millions, certainly.
You also have to balance out all the people will stop doing work that benefits society with the group of people that create something of huge value in the they used to spend doing wage labor. Traditionally it was rich people who therefore have a lot of free time that made all sorts of advances in science and mathematics (see all the lords hanging around 18-19th century science). The same logic goes for forming businesses unless a massive percentage of people don't work - it takes a ton of money to start a business because you still need to eat ...
I read Floornight because of this post and it was very good. So, there was at least some benefit to making this fanfiction.