Fixing a whole message flow in a node

is it possible to view a message flow inside an node, without using grouping,
may be in other words I want to place an react component inside a node, which can be collapsable and expandable

What do you mean by a “message flow”?

Nodes and Links cannot contain HTML. That would be very inefficient and would also restrict how we can render diagrams to images or to SVG or to other media.