I've seen the idea of retroactive funding for impactful projects tossed around a bit. An obvious case for this that comes to my mind is Eneasz Brodski's production of an audiobook for Harry Potter and the Methods of Rationality. I imagine that this audiobook has significantly increased the reach of the book. (And, personally, his audio production deserves most of the credit for why I consumed the book in entirety.)
Has such a retroactive grant been done? If so, I can't find any evidence of it.
update 1: Eneasz has confirmed that there has not been. Is there any reason why this might be a bad idea? This seems like low-hanging fruit to me, so I'm unsure why this hasn't been done.
update 2025: this was never funded afaik
Permissionless economies are much more efficient.
For funders: Distributing cash upon results being shown is a lot easier than vetting and modelling who and what will succeed, not to mention involves better incentives.
For doers: Barrier to entry is much lower, I just need to do the thing (that i probably enjoy), not this additional labor of getting a permissionful grant (which i will not enjoy).
For many doings, doers might require upfront payment or gaurantees. However, in very many cases, probabalistic recognition and payment is sufficient.