Yes, this is possible. You can compile your own HTML and upload that to the JourneyApps code editor and embed it using the HTML component.
Another option is to use online chart generation services, such as Google Charts or ChartURL. You can then invoke the creation of this via CloudCode and store the charts in the DB or, depending on the service, embed the response URL as the
src of a JourneyApps
html component [this specific part will only work if the user is online]. This is probably the easiest option for generating and displaying charts.
For a more advanced HTML component that can communicate with the JourneyApps container e.g. to send data to the HTML to render something, you will need to use is the JourneyApps iFrameClient.