Hi Juzo, I am sorry you are in a war torn nation.
Not that I know anything about this™ , but ….
In the case of DJI, the remote<->drone link is essentially wifi. There are many tools to hack wifi around like wireshark, as a place to start.
Your focus initially should probably be toward ways to either hack into or interfere with wifi.
That said, the exploits “I don’t know about” involve things like brute force password attacks, which can take days, and therefore is not much use in a real time warfare situation.
Jamming a signal simply means transmitting a strong enough signal at the same frequency such that it “covers up” the control interaction, but this does not allow you to take over control, only to block control, which is of marginal utility.
If a UAV loses control communications, they enter autonomous mode and go to their preprogrammed destination to provide their earth shattering kaboom.
Unless you can access the secure data link, you’ll never be able to have authoritative control.
Best of luck.