This is correct, you still have to go through firmware to gain access to the block/page on “disk” and if the firmware decides the block is invalid than it fails

This is correct, you still have to go through firmware to gain access to the block/page on “disk” and if the firmware decides the block is invalid than it fails. You can sidestep this by bypassing the controller on a test bench though. Pinning wires to the chips. At that point it’s no longer an SSD.