I'm using the Raspberry Pi Compute Module 3 (CM3) in my latest hardware product for networking and user interface function, as it has small form factor and solid availability (until 2023 according to the datasheet).
I would like to bundle my software into the on-board-flash in a way that it would be difficult to get it off from there and modify. I understand that if someone really wants to get my software then they can just unsolder the flash from my CM3 and read it on some other system, but is there a way to protect the content (like micro-controllers have the fuse bits to make the flash content non-readable over the debug/programming line). My Linux image is read-only. All the data generated by the device is saved on external SD card and configurations are held in external FRAM.