A SWOT analysis is a thorough examination of the strengths and weaknesses of a business, the opportunities open to it, and the threats it faces. The first two areas focus one's attention within the business, while the second two are used to examine its environment. First, you need to choose a local independent store. A good example might be a delicatessen, a type of business which is often independently run, and of which there are several in most towns (including Hartford, Connecticut).
In the first paragraph, give as many details as you can about the store. How big is it? What range of produce does it stock? Does it include a café or other associated business? What sort of clientele does it attract? Any financial details you can find out will also be of use.
For strengths, consider what this store has to offer. Does it have a good range of produce? Are there many items which are unattainable elsewhere? Does it stock high quality meat, cheese, vegetables and other items from local producers? Does it have good organic credentials? Does it have knowledgeable, enthusiastic staff who can tell you where you food comes from? Are prices reasonable? If the answer to any of these questions is no, these can go in the next paragraph as weaknesses.
In terms of opportunities and threats, the COVID-19 pandemic certainly counts as both for such a business. With fast home delivery and a strong online presence, a local delicatessen may be well positioned to take advantage of a situation in which more people are staying at home, particularly when it has a strong existing customer base. Your final paragraph, on threats, should identify the store's main rivals in this area, from other local delicatessens to huge corporations like Amazon, which also delivers groceries.