@Trigani
I rememeber [@Dihn AronMK] and I agreeing on Khyber Pass guns for weaponry.
A thing to remember about reproducing modern tech is the materials that go into it. I know people like to tote around knowing how to do something is the end-all be-all of continuing the standard of listening.
But really it's a third of the battle.
In the present situation you have factors to complicate things so you should always take those into consideration. A lot of heavy chemical production and even producing oil basically requires oil to make oil. Distilling or fracking high-grade industrial components like plastics and rubbers will require on some level the possession of plastic and rubber seals to keep the high internal environmental pressure to produce something such as rubber. Wood-based seals (cork from the cork tree) and leather are all far too porous to let you even make the best quality product if at all (on crude oil pulled from the ground the best you might be able to produce is crude kerosene and some crude low-efficiency gasoline, but no high-grade fuels or the base ingredients from rubber and plastic production).
A jump-start on this would be to obtain natural rubber but rubber trees would not grow at all in the Americas framed in the map. Natural rubber is very fickle to grow and very complicated.
And passed all that you need benzene compounds and vulcanization fluids and basically to hold that into the stills where they're heated and mixed to make synthetic rubber of the 27+ grades there are means you will still need rubber.
The other issue to keep in mind is the man-power ultimately available to us. With everything suddenly dead and about a century worth of rot we would have well lost the components needed that makes farming today so hands free as well as a lot of other jobs. We literally will be back to societies who had to devote as much manpower to farming and agriculture as we had in the 19th century. We don't got mechanical tractors even anymore. So there'll be more hands in the field, in the woods, and in the mines than we might have today, which translates directly to less in the lab, less in the art studio, or less in the military.
It's difficult to accurately access those numbers but should be kept in mind. The base I used to run off of was ten-percent in the military but that's even pulling it. Ten percent would be like what you produce in a desperate attempt to hold on without nuking your economy long-term. Even the five-percent I pull might be high, but whatever. Just keep it in mind there'll be a lot more people devoted to physical labor than not.
I also mention rubber and plastic because it's one of the most important industrial materials in the modern society. Without it we pretty much lost everything. Take a serious moment some time to look about your house at all the products that use plastic and rubber or might have bee produced with industrial rubber sometime down the line. It's pervasive as fuck. So WW2 equivalence might not even be right and we could actually be looking more at mid-19th century. Society is back to wood and iron and not aluminum and vulcanized rubber.