I believe the battery voltage and gauge/length of wire would determine how hot it would get inside the glove.

Maybe try some experiments with different batteries and wires. All you will need to do is connect a single wire to the pos and neg sides of the battery.

This is potentially dangerous and really needs to be handled by someone with an electrical background

One way
Another way

Welcome to Fluther.

If your engineering specifications – such as they are – tell you the method that you are required to use to heat the trigger finger – “a wire inside a glove” is pretty specific – then they should also detail the specifics of how that is to be accomplished.

I would, instead, reject the whole scheme and brainstorm from first principles: “What needs to be triggered, and how can that best be accomplished in your particular extreme climate?”