A sufficiently large scale nuclear war could easily set humanity back to preindustrial levels of development. And it's not certain to me that we would ever get back to where we were. The first industrial revolution was bootstrapped by easy to get to minerals and fossil fuels. Many of those have been used up.

The speed of bootstrapping would be greatly increased by the knowledge we have. Even a very serious nuclear war would leave significant caches of scientific and technological knowledge. Galactic timescales are so large that we could easily afford to spend thousands of years rebooting, even do so many times. Of course if there's some technology that is even more damaging (and easier to make) than nuclear weapons, we might have a good great filter candidate.

I personally believe the Great Filter will be psychological. Our will to achieve things and propagate is in our brains. Future generations are likely to ask "Why do we have to move around a lot of matter and energy to achieve very minuscule electrical changes in a bunch of neurons, when we can short circuit the whole process and do those changes directly?"

We're already kind of doing this with drugs and digital simulations...