@ramsey The LernOS peer learning guidelines could be an example. There are several guidelines on how to acquire or improve skills that have been written and are maintained by people in their spare time. Making use of these guidelines is free for individuals and companies, and I‘ve seen companies integrate them into peer learning systems within their organisation.
https://lernos.org/
@_holger Flowlance is a Czech Company. I got an appsumo lifetime deal a couple of months ago, and for my use case (so far just one low-priced pdf) it‘s working fine. Referral link: https://www.flowlance.com/?ref=deltasig, non-referral link: https://www.flowlance.com/