Food distribution and emergency services typically get taken over in good part by the military.
Necessary food production is generally outside of cities.
All Healthcare except for what is immediately necessary similarly is not needed, same for vehicle repair and so on.
Keep in mind, this is only for a very short period of time. You don't have to deploy anywhere near the population needed for a sustainable organization.
For the US for example, there are 55 million "essential workers". 11 million of those are in agriculture or restauration (so either outside of a city or dispensable). 10 million are in finance or residential/commercial facilities services, most of which is preemptible for a few weeks. 4.5 million are in governmental services which can largely either be done remotely or preempted for a few weeks. Realistically you're looking at 25 million or so when you cut down on everything that isn't necessary and have the military take over a lot of the work.
If you want to see what thay looks like, you can look at the Wuhan lockdowns and to a lesser extent various strict lockdowns in third world countries.
Necessary food production is generally outside of cities.
All Healthcare except for what is immediately necessary similarly is not needed, same for vehicle repair and so on.
Keep in mind, this is only for a very short period of time. You don't have to deploy anywhere near the population needed for a sustainable organization.
For the US for example, there are 55 million "essential workers". 11 million of those are in agriculture or restauration (so either outside of a city or dispensable). 10 million are in finance or residential/commercial facilities services, most of which is preemptible for a few weeks. 4.5 million are in governmental services which can largely either be done remotely or preempted for a few weeks. Realistically you're looking at 25 million or so when you cut down on everything that isn't necessary and have the military take over a lot of the work.
If you want to see what thay looks like, you can look at the Wuhan lockdowns and to a lesser extent various strict lockdowns in third world countries.