Production deployment guidelines for ESP32-C3

[zigenz]

Hi there,

We have developed a product using the ESP32-C3-MINI-1-N4 which is working well. We now need to transition the firmware binaries (bootloader + application) and relevant signing keys into a package, and specify the programming hardware for the contract manufacturer. We currently have a TagConnect header provided on the board to enable programming.

I have a number of questions I'd like addressed, namely:
1. I noticed that on a virgin device (i.e. not a devkit), I was unable to program over USB. I had to pull IO9 low, reboot the device, and program via the UART. Is this the only way to program a virgin device?
2. What are the basic rules of thumb to protect firmware images on the device?
3. Is there a recommended production programmer available for purchase?

Ideally there is a production programming reference guide I could refer to, but I've been unable to find one. If it exists and someone can point me to one, it would be great.

If not however, it would be great if someone could please address my queries above. Thanks!