Need to Create a full-fledged drag-and-drop flowchart builder with arrow connections in angular,
I have tried drag n drop feature of todo and done example using material angular version 16 in angular 16,
but i need a flowchart builder where cards are connected by arrows when drag and dropped
In a commercial context, you might want to look at one of the (few) but sophisticated flowcharting and graph visualization diagramming libraries. There aren't many that are implemented specifically for Angular (because Angular seamlessly integrates "third party" components), but this type of application quickly becomes very complicated and running your own solution will quickly become infeasible and many of the simple solutions quickly fall short.
I work for the company that creates yFiles, and there are a number of fine examples that show integration options with Angular, here. I do not represent my employer on this platform, but I wholeheartedly recommend the library, specifically for flowchart like diagrams, because of it's interactive options and automatic layout that is helpful for flowchart-like diagrams. This is my personal opinion.