I store the states for Items I want to chart into InfluxDB using persistence and I used Grafana to generate the chart. See the InfluxDB+Grafana Tutorial for how to set it up. I believe Grafana works with MySQL/ MariaDB and a few other databases as well.
You can embed the charts from Grafana right on your sitemap, but I like to embed static images instead so I used the Grafana Image Renderer.
You will need to host InfluxDB and Grafana on some other machine separate from your HestiaPi. There is simply not enough RAM to support them and OH on an RPi 0.
If you wanted to so it all on the HestiaPi, you can use rrd4j as your database and the chart element. Those graphs don’t look as nice nor are they as flexible, but it would let you put it all on the same machine. NOTE: rrdj4 does not store Switch Items so you would need to use a proxy Number Item to generate those bars showing the ON/OFF status of the heater/fan.
No but some charts could be. And the data for those charts are generated from the HestiaPi.
Among the many things on my to-do list is a tutorial showing who to create charts and an emailed monthly report showing how much time was spend heating/cooling/humidifier/etc.