A platform where people specify what they want to understand and pledge a $ bounty to whoever first explains it well enough.
People then submit concisely written explainers with references that help the learner scale-up knowledge as far as they want to take it.
Video tutorials could also be submitted to take the learner through a how-to process. For example how to build a drone, how to plant a forest using the Miyawaki method, etc.
The knowledge is shared publicly and can be used by anyone free of charge. The person who pledged the bounty paid for it so that the future learners can benefit as well.
While the request for knowledge is actively awaiting submissions other people can contribute to the bounty to make it more lucrative.