Display a new entry modal when clicking on a relation field For a complex website we have nested a relation field inside a matrix.

It makes little sense for us to show the list of already created entries so we would prefer to directly display the new entry modal when clicking on a relation field. Our goal is to facilitate the editors lives and thus avoid multiple modal nesting... (See below).

Thank you in advance for your advice. Peace.
I'd rather look into nesting Super Table fields within your Matrix block types than relating Entries. The Entry element type and its relationship field come with a lot of inappropriate UI for the use case you're trying to solve.

Another approach would be to write a plugin that provides its own element type and relationship field / modal UI.