Perhaps randomly changing the layout? Sometimes the keys are presented in a circular format, another in a figure-8, zigzag, odd numbers at the top of the screen

Perhaps randomly changing the layout? Sometimes the keys are presented in a circular format, another in a figure-8, zigzag, odd numbers at the top of the screen, even at the bottom, etc. Another tactic might be to have randomized extra keys that show up in a different color or position that aren't a part of the actual PIN but that must all be pressed, in any order, to intermix in the sequence as the the real PIN is entered in proper order. The extra numbers obfuscate the real PIN. Say, the real PIN is 18145 but 4 extra keys in a distinct color or motif are presented so that the key presses might be 1-8 (real) 8-4 (false) 1-4 (real) 3-6 (false) 5 (real) but the false keys are different each time. It wouldn't matter what order the false keys are pressed or when in the sequence they are pressed as they are ignored by the real PIN mechanism.