There’s a circuit in the trigger. It’s not just electrical wires. You may not be able to build it on your own.
You can use string.
Multiple people have done this.
You can also use a Raspberry Pi Zero, but you’ll need to add a physical button to the Raspberry Pi.
Numerous other triggers have been built.
This solution by @Bob_White might be a good one for you. Maybe you can buy a unit from him?