As for electronics:

Reverse enginering of old ones/projecting some + some FPGA or arduino maybe. Costly and can be big,but it could work some time if shit hits the fan.

If not some "junk" chips and parts too. If I were mechanic I would visit nearest junk yards. Crushing and scrapping whole cars is cheap and not requires paying to big salaries to employees but there are some parts in cars that are pretty good.

I heard you Americans have terrible customs about cars and not enough knowledge about conservation,but thing is some junk part are quite in good shape - the problem is it wasn't affordable to recover it because of costs of workforce. Old one but working may be not the best but may be however working.

In Poland because our salaries are shitty "lower class" and "middle class" usually buy used cars,and if somebody in family have basic mechanical knowledge then hurray ! - we buy some parts from junkyard same original ones and...

Of course salaries in USA are much higher but as it will be less available that might get affordable.