It can't. The RP2354 is just a RP2350 and a flash chip in the same package, and the QSPI pads are also bonded to package pins (so that you can use the second chip select for PSRAM etc). So with the device as announced there's nothing to lock/disconnect - unless you are going in there with an angle grinder or the like to physically remove the pads.The simplest solution would be to use internal flash, without any encryption, and lock it to be accessed from outside.
Not sure if it can be done easily (like locking/disconnecting the external OSPI pads) or at all.
Of course they could have made a version without the pads bonded, but they decided not to (probably rightly: omitting the pads doesn't make it very secure as an attacker can fairly open the package and extract the code; conversely if you use the security features as intended you don't need to restrict physical access to the flash).
Statistics: Posted by arg001 — Wed Sep 25, 2024 8:25 am