Log/Chart Data provides purely on-device charting.
(This, in case you're wondering, is a three-day chart of four temperature sensors in my two-bedroom condo... and is why I built this.)
Code (and better documentation) are at GitHub - robomac/Log-Chart-Data: Fully on-device event Logging and Charting system for Hubitat Elevation (HE)..
It consists of a parent-app, "Log Data", which captures events to JSON, and a child-app, "Chart Data", which graphs events into SVG files.
The results on a DashBoard can look like:
Please feel free to ask for additional features, including higher speed modes, other data exports, etc.
