Is there an iPad with no built in magnets?

No. iPad and iPhone both incorporate magnets in their construction.

Given your issue, you need to be aware of this specific warning/advice from Apple concerning possible interference with medical devices:

About potential magnetic interference with medical devices - Apple Support

No. All iPad models include magnets to attach the magnetic smart covers and Apple Pencils.

The magnets on an iPads are not very strong, so should not interfere with anything.

Unless the iPad is placed on his chest, or very very close to it (less than 6 inches away), the magnets should not interfere with the Pacemaker.

You should consult with your cardiologist however, they can tell you more about the sensitivity of the Pacemaker to weak magnets such as those in an iPad.