One or more pinboards are placed on key office locations, such as cantina/cafeteria/lobby/parking lot/etc.

Big advantage of this idea is it works offline! A very simple, fast, effective and budget-oriented solution. On top of that, the idea is scalable to any level of employment - from blue collars up to top management!

I feel that more people nowadays are tired of too much technology - apps, AI, clouds, etc. and would prefer a simpler, human-centric old-school learning approach.

You pin a question and someone answers, or at least points in the right direction. Such approach brings increased communications between colleagues and sparks a beneficial discussions on work-related topics, improving team morale.

Keep Leaderboards about who posts and answers most questions, combine these with incentives and through a simple learning hack "pin a question - get an answer" you'll end up with a long-term scalable learning system.