How to create a custom react component in Form IO?

Question

There has been so little documentation, Github Issues and examples (not on react-app-startkit though) of thoroughly creating custom components in Form IO with Reactjs, and it took me countless hours to figure something workable out.

Thus, I think it has the values to ask a question to organize the different methods available (with either functional or class components, as you like), and how they could interact with <Form> and <FormBuilder> components.

Below is the basic way mentioned in the documentation to create custom components in plain JavaScript:

const Input = Formio.Components.components.input;
class MyInput extends Input {
  ...
  ...
}

Thank you for all the help.