Inspired by this Mastodon account, I programmed an ESP8266 microcontroller to act as a traffic light, indicating the current electricity mix. Check it out on Codeberg! It uses an API from the Fraunhofer Institute and the parts cost around 5€. In my shared flat we use it as an indicator on when to run demanding devices, like the washing machine.
Automatic delay and time adjustment should be standard for consumer devices and electric car charging that consume lot of energy, and don’t need to be activated immediately.
For years and even decades, it’s been possible to setup water heaters to activate during low-rate electricity hours, and store the hot water for later.