Get members name on signup without portal

Is there any way to get the members name on ‘free’ signup through code - without having to use portal?

I’ve had a read through the docs but can’t seem to find any mention of it.

I am updated to Ghost v4.1.0

I’m guessing the docs still need to be updated for v4?

Using data-members-name on an input works.

<input data-members-name placeholder="Enter your name" id="name" name="name" type="text" autocomplete="name" required />