Visual node builder for functions

We have several tools on the web that makes it easy to setup functions.
Altogic, Zapier, Integromat, N8N and others.

For those unfamiliar, it looks like this, at the right we have Zapier, and at the left side we have N8N:

![image](

How would one go to start creating the feature, which would be the inner functioning and an internal page for this? I think that we could have our custom coded functions with defined input and output.

After this is made, we could look into adding some premade nodes (premade functions), the ability to import/export premade nodes and also attain premade nodes from a public repository of nodes.