The drone is 500$. If the board is 300$, it makes it a lot more expensive. What's the value of that board? How much does it help? Remember that you need to fly it with FPV to the place where the operator can select the target. So you have a radio link at some point, that can be jammed.
I see on the rpi website [1] that an RPi 5 costs 120$. That's 25% of the price of the FPV drone (500$).
Then you have to integrate that RPi to the drone, both mechanically and software-wise. From YOLO, you need to actually get into commands for the autopilot. There is work involved.
And another question is: can you order millions of RPis like this? If not, what is the cost of alternatives?
Not saying it's impossible, just saying that people tend to underestimate those questions. I know it from experience, I have seen projects fail because of that.