If the government response didn't prevent people from taking at-home tests, and had more nuance than 'shut down all "non-essential" activity', JIT inventory would have kept working on the whole. "Non-essential" was extremely poorly defined.
It was poorly defined, in the sense that nearly every single economic activity was "Essential" under the definitions set out by governments across the world.
If you provided any kind of service or product that was consumed by an essential business, you were also essential. My wife works in a small company that sets up tech conferences. They are... Essential (Despite not having any work for the past year. If nobody wants to pay you to do any work, I don't think you are essential, but I'm not the guy in charge...)
Looking at the definition of "essential" most places in the West, it was nearly everyone!