I've been working on something very similar in the past three weeks. Just out of curiosity, what have you used for the layout?

In my project I used reactflow for all things graph and dagre for the layouting (together with some custom hooks to make it work with variable size nodes).

I'm not sure if I will try to monetise it or if I will simply open-source it. Probably the latter because when building time is over and marketing time starts, I get very bored and lose interest soon.