The transit stop use case really does seem to be ramping up, including the Massachusetts Bay Transit Authority currently adding them to most surface Green Line stops: https://www.mbta.com/projects/solar-powered-e-ink-signs
Interesting. Now I'm curious about the tech used behind it to transmit the info accross the network. I'm wondering if a LoRa/LoRaWAN-based mesh network could do the trick to avoid using some kind of cell data or wired infrastructure, but also be energy-efficient enough to work using only solar power.