Can the P4040 eSPI controller address 4-byte (32-bit) addressable EEPROMs in any situation?
Yes, eSPI controller addresses 4-byte addressable EEPROMs in any situation.
For P4040, is it possible to boot from a 4-byte EEPROM using the on-chip ROM?
No. The software in the on-chip ROM only supports 16-bit addressable or 24-bit addressable EEPROMs.