Q)Is my understanding correct that the Cypress S34MS04G2 requires host-side ECC and does not have on-chip ECC?
A) Yes, it requires host side ECC.
Q) Is there any other Cypress SLC NAND alternative with on-chip ECC (I am not looking for an eMMC solution)?
A) No we do not have any NAND devices with on chip ECC.
The error correction code whether it is hardware or software is the responsibility of the host system. The NAND simply provides the storage area and the data blocks to hold the error code bits in use by the error correction method of the system. The memory does not do anything other than to store it for the system to read back with the data blocks. The system generates, stores, reads back, and corrects data blocks & ECC bits. The controller should be able to report how many bits were corrected.