Scheduling all-day interviews in Pinpoint is almost identical to the process of scheduling any other type of interview. The only difference is one check box in the Interview Type configuration.

In the Interview Type just set the below setting as 'All Day Interview':

Then, when you head to the 'Availability' tab when configuring the interview you'll notice that the calendar is slightly different to usual. It'll show you days rather than hours, and all you need to do is click on any day to select it as an available option for the candidate to choose:

When the candidate views the interview scheduling page, they'll only see days to choose from but not specific times, like this:

The language is also tailored to the fact that it's an all day interview, on both this page and in the email confirmation sent to the candidate as shown here:

The calendar attachment that the candidate receives, which is attached to this email is also set as an all day event.

How to schedule an interview
How to set availability for interviews
How to create an Interview Type and assign it to a job