> 1. Bootstrap a smithy

I would recommend learning about what is involved in this step, before moving on to step 2.

https://acoup.blog/2020/09/18/collections-iron-how-did-they-...

This process is incredibly difficult, made moreso by the lack of easily accessible surface ore/coal. Also, keep in mind that when agricultural productivity is in the pits (Due to a lack of tooling, chemical feedstock, massive infrasturcture projects), and when you don't have the ability to make synthetic clothing (Which leads you to working with natural fibers, which is an incredibly labour-intensive process[1]), you aren't going to have the spare calories, or the hours in your day to 'just bootstrap a smithy'.

[1] https://acoup.blog/2021/03/05/collections-clothing-how-did-t...

Where do you get the copper ore in this scenario? Existing natural easy-to-access ores have been mined out already. Would it be possible to mine the detritus of our civilization to get these ores?

In this scenario, the world would be covered in easily accessible metal scrap.

It's all well and good to be optimistic, I'm a MacGyver too, but when society only gets one roll of the dice to restart after a mass extinction event I don't think it's advisable to discount the difficulties and challenges society will face trying to restart, with access to accessible energy sources being a major component of those challenges.

Maybe my brain's groggy, but how are we achieving self-excitation in this scenario? (I'm assuming there's no magnet in your setup as it's not explicitly called out.)

No. Of course you need a magnet if you don't want to build a more complicated self-excitation design (building that would be quite the feat given the circumstances) or want to use a smaller dynamo to bootstrap an electromagnetic dynamo or even alternator.

But it's better to start with a magnet and stick to easy-to-debug stuff that can be eyeballed start to finish.