I shared your sense in #3 initially, but 2 things changed my mind: the fact that Open Phil has already granted ~$100M/yr in 2021 and 2022 (h/t MichaelStJules’ comment for bringing this to my attention), and Megaprojects for animals, a longlist of “projects that further research might reveal would cost-effectively absorb $10M+/year”, your idea re: funding research included, which seems to promise shovel-ready opportunities for scale-up beyond $100M/yr (let alone $100M granted over an arbitrary period of time, as the problem statement asks).
I shared your sense in #3 initially, but 2 things changed my mind: the fact that Open Phil has already granted ~$100M/yr in 2021 and 2022 (h/t MichaelStJules’ comment for bringing this to my attention), and Megaprojects for animals, a longlist of “projects that further research might reveal would cost-effectively absorb $10M+/year”, your idea re: funding research included, which seems to promise shovel-ready opportunities for scale-up beyond $100M/yr (let alone $100M granted over an arbitrary period of time, as the problem statement asks).