I need to get more info from users upon signing up

Hello,

So I understand it's not possible to add extra fields to the protected-content sign up form.

1/ can you confirm my understanding is correct ?

2/ I do need to retrieve more information from my users upon signing up though (address, phone number, etc...). Do you have any creative solution that will allow me to get it ? for example, is there a way to have a 2-form sign-up process : (1/2) would be your default form and (2/2) would be another form with the extra info I need.
I'm open to suggestions you may have

3/ I don't know what gravity form is do but I've heard mentions of it, would it help me ?

Thanks a lot for your help,
Thomas