I LOVE this idea! I was about to suggest the same thing (well, I kind of already did in March), but I only just found this thread.
I agree with @Klaustrophil that some level of specification would help, and also with @redcloud that an existing track record would help increase the trustworthiness of this approach.
If MOD are too busy to implement this process, we could potentially just use an existing FLOSS crowd-funding platform like https://gitcoin.co/ or https://www.bountysource.com/. For example I’d happily contribute to a bounty for someone to finish Freeze pedal on the horizon?.