I am curious about the mechanics of how the projects will spend this money. I have had quite a bit of professional experience working as a developer within an open source project and I honestly don't know what we would have done had someone showed up with a one time payment of this size.

The dollar amounts are too low to hire a full-time dev. They presumably have insufficient volunteers or they wouldn't need this money. So I am guessing that they will be offering existing volunteers some money to devote more time to the project.

Another alternative would be hiring in some contractor who has no prior relationship with the project but having someone who doesn't know the project come in and implement something before vanishing and leaving everyone else to maintain their stuff is unappealing.