Chips that can’t fit on a 76mm board do not exist in any market. There’s been some fringe chasing of waferscale for compute, but it’s a nightmare of cost and yield with zero applicable benefits for storage. You can fit more chips on a bigger board with fewer controllers, but a 3.5" form factor wouldn’t have any more usable board surface area than an E1.L design, and not much more than an E3.L. There’s enough height in the thickest 3.5" to combine 3 boards, but that middle board at least would be absolutely starved for airflow, unless you changed specifications around expected airflow for 3.5" devices and made it ventilated.
Chips that can’t fit on a 76mm board do not exist in any market. There’s been some fringe chasing of waferscale for compute, but it’s a nightmare of cost and yield with zero applicable benefits for storage. You can fit more chips on a bigger board with fewer controllers, but a 3.5" form factor wouldn’t have any more usable board surface area than an E1.L design, and not much more than an E3.L. There’s enough height in the thickest 3.5" to combine 3 boards, but that middle board at least would be absolutely starved for airflow, unless you changed specifications around expected airflow for 3.5" devices and made it ventilated.