In short, we know of only one working flash loader for 602 and the situation is even more dire for 70. :-(
I evaluated seven different programs that included a CLI to test BL60 specifically, and consulted with experts on the Bouffalo parts. We all three agreed that the "draw an owl" part between generating a .bin and seeing it appear on the device is frustrating and during development, can be a huge time sink (did I move the jumper too soon? Oh, I just debugged the executable that was left in flash because the upload failed?) and needlessly frustrates developers.
We had all three tried various JTAG tools (on BL602) and knew that none board/software combination (which often included OpenOCD) from the likes of Segger, Sipeed, FT232H, others could successfully write to flash, even when they could halt the processor, introspect registers, RAM, and bus devices, and restart the device.
Of those seven, only one could be reasonably considered "working" on the the three major OSes. We found blflash from Spacemeowx2 to be the best tool for programming BL602, BL604 on MacOS, Windows, and Linux. We all agreed to center our collective recommendations, like writings, and effort behind that one.
BLDevCube offers lots of functionality we (I) don't need, but the absence of a command line is a deal-breaker. I'd hope that breaking out the minimal "send argv to the device" main(), using defaults for clock speeds and all those other strange knobs to turn, should be easy to abstract out. Also, DevCube has basic functions broken and I've had the engineering teams stumped for months on that one. At one time, I was able to link my program and shoot it into the 706EVB and run trivial code from RAM that way using GDB. It's from memory and I don't recall if OpenOCD was involved or not.
We just don't have a working solution for BL706 yet and we're designing a new product that's outgrown the BL604 and needs more GPIO.
Also, ahem, one direct competitor to the 706-class chip emulates a USB CDC mode in their boot rom and uses DTR and RTS for their equivalent of reset and PIN 8/PIN 28 boot mode and offers a second /dev that's used for JTAG. Power, console, jtag all over the same single commodity cable - they probably don't even need the 24-pin versions. No jumpers. It's pretty sweet...except that it has about the same GPIO cont as the BL604, so that's not really a useful alternative for us anyway.