Can I connect the payload Darcap 25 to a USB-C adapter?
No, you cannot. Doing so will damage the payload. Therefore, it is not possible to program the payload without a drone.
What operating system does the Darcap 25 run?
The operating system on the Darcap 25 is NVIDIA Jetson Linux 36.3. This provides the Linux Kernel 5.15, UEFI based bootloader and Ubuntu 22.04 based root file system.