Use keyboard to move cursor on iPad Pro
Place two fingers on the keyboard and drag the two fingers around to move the cursor.

On iPhone, you don't hold a specific key — the action is initiated with 3D Touch anywhere on the keyboard with one finger. As you mentioned, iPad does not currently have 3D Touch, but you can use two fingers to manipulate the cursor like you did on your iPhone with one finger. The iPhone functionality came after the iPad keyboard cursor trackpad was implemented.