In an op-ed to the Washington Post, a literal professor of infectious disease exposure says that you're unlikely to be infected through groceries or packages, and if you're worried, even a few of the steps people are adopting should help reduce the threat of infection enormously.
Yes, the virus can be detected on some surfaces for up to a day, but the reality is that the levels drop off quickly. For example, the article shows that the virus’s half-life on stainless steel and plastic was 5.6 hours and 6.8 hours, respectively. (Half-life is how long it takes the viral concentration to decrease by half, then half of that half, and so on until it’s gone.)
Now, let’s examine the full causal chain that would have to exist for you to get sick from a contaminated Amazon package at your door or a gallon of milk from the grocery store.
In the case of the Amazon package, the driver would have to be infected and still working despite limited symptoms. (If they were very ill, they would most likely be home; if they had no symptoms, it’s unlikely they would be coughing or sneezing frequently.) Let’s say they wipe their nose, don’t wash their hands and then transfer some virus to your package.
Even then, there would be a time lag from when they transferred the virus until you picked up the package at your door, with the virus degrading all the while. In the worst-case scenario, a visibly sick driver picks up your package from the truck, walks to your front door and sneezes into their hands or directly on the package immediately before handing it to you.
Even in that highly unlikely scenario, you can break this causal chain."
Lots of good information in here, check it out.