Hi,
I just wrote some lines to be able to generate simple bitmap charts from an entity (sensor) history for older/special devices. For me it was useful for a Garmin Watch and an E-Ink display, maybe some of you have the same requirements for these special cases, so I will share the Add-on.
The Add-on can be found here as repository:
It is also useful in combination with notification services like Pushover (seperate HA integration). You can send small charts attached to the messages (e.g. rain last 24h, or water leak alerts).