What i read elsewhere is that Xilinx provides this sort of security feature, where you can "fuse" parts inside the chip after you flash the firmware to it. This is probably what the rumored Russian malware that damaged nands did, but I'm unsure if the S9s have this.

What appears to be certain, is that the S19 ships with this "feature", and the newer firmware updates in the rest of the S17 family do this as well. So if you even have even the slightest plan to ever try Braiins OS in your S17, make sure you do not ever update the firmware. Because, it is yet to be seen if these could be bypassed somehow (without getting a solder gun, that is).