I currently have a TreeMapper diagram where I map from source groups to a destination group that represents a form. However, I’m wondering if it’s possible in the destination group to render a form and map directly to those fields. ?
It’s not easily possible to render HTML into a Node, though you could overlay HTML over this node, for example, when its selected.
One possibility is to render some HTML as a SVG ForeignObject and then paint that SVG to a GoJS Picture: HTML Rendering
But then you cannot interact with it.
Another option is to make the HTML form, size it appropriately (possibly the identical bounds of the node, possibly not), and show/hide the HTML based on the selected node, always on top of the Diagram. This is doable, and many customers do it, but it can take some time to get it right. This is how the built-in TextEditingTool works, for example.