I love the sticker idea to break habits. Very smart.

Unproductive work can multiply, so your colleagues start wasting time, too. For example, if not carefully managed, initiatives that started for valid information, optimization or standardization efforts can turn into wasteful data collection busy work with little or no returns.

You might like an ecologic option. Think of a fiber optic cable or mirror tube that can be placed from a roof to any room in the house. Could not find a good english translation, but similar to this one: https://www.lichtkamin.de/

Have you seen any options that don’t require a fat tube running through the house?

The option of using fiber optics cables to redirect sunlight is discussed in this article: https://www.buildinggreen.com/blog/fiber-optics-daylighting One of the companies mentioned looks pretty interesting: https://himawarisolar.com/

Definitely the problem to solve. I thought about splitting this up into hundreds of optical fiber filaments. These could fit in wall elements or next to other pipe elements.

Etendue will limit your success, though. Especially if you don't track the sun (or there is a cloud in the way).