Not in this field but, if you're willing to sacrifice performance for security (by avoiding closed, western, hardware) how hard would it be to for a group of top hardware and software engineers to make a secure smartphone?

Id gather you could go very far with the following list:

- Proved correct micro kernel

- Encrypted messaging by default

- Encrypted memory

- Encrypted messaging between processes.

- hardware switches for modems, peripherals and battery

Technical feasibility one way or the other is meaningless in the face of the power of Capital. IMO, Capital won’t allow the creation of devices it cannot control. So truly secure devices are a pipe dream — again my opinion.

I believe a proven correct micro kernel for a production system in smartphone scale is a sufficiently complex engineering task.