I’m guessing repair knowledge would be more important in the short to medium term.
Outside of that I think you need to work your way back up the tech chain starting with the wheel, leapfrogging as much as you can. But you don’t want to leapfrog over early tech like industrial machines, transportation, etc. and start working on web apps too early.
Securing fuel for the motor, let me down the dark side of thought which is either protection or "just take it". I bought guns and learned how to use them (safely!).
Of course, later I learned about gardening and self-sufficiency and being off grid. While I've never been off-grid, I started to do thought exercises and preparation. I was never a "prepper" per se, but I learned the basics because the early 2000s created a lot of global uncertainty.
Circling back to tech, I started to learn morse code so I could HAM.
Power + communication + protection and food are the basics (not necessarily in that order).
I have some survival books and Wikipedia downloaded on a disk in a faraday box, but I'm not sure how long I'd be able to access it - it largely depends on the type of event.
A significant power outage is all it would take to simulate technology life in a disaster scenario. My servers/homelab wouldn't be of much use in a disaster, but being able to read would be tremendously useful and valuable.
Use a diesel motor and grow vegetable oil. Or culture the right kind of algae.
Generating power with a lawn mower? Would never have thought of that.
Of course, since it is fuel limited you'd want watermills and windmills, along with other manual (human or animal) powered systems, for driving machinery most of the time. Now, if you can get a diesel system going then you have the possibility of using biodiesel which would alleviate some parts of the fuel problem, assuming you have a source to produce the biofuels from.
As a bonus, I completely forgot to mention my homebrew ethanol still[3]. I applied for a small fuel producers license from the ATF/TTB which required me to denature it so it could only be used for fuel purposes.
[1] https://chrisbergeron.com/2008/08/24/homebrew_generator/
[2] https://chrisbergeron.com/2008/01/21/metalcasting_furnace/