Selling paint? Probably not essential depending on the situation or it could be done remotely. If they supply protective paint to essential businesses then I could see it though. Liquor stores are another example that seems absurd to be open, but they help stop alcoholics from crowding hospitals with withdrawal symptoms. That said there are a ton of things open that shouldn't be. Gamestop was almost labeled an essential business for fucks sake.
Selling food? Definitely essential, but fast food restaurants maybe not. Stopping delivery and pick up from restaurants would put a significant strain on grocery stores and would lead to a large amount of food waste as well as restaurant closures. That said there's plenty of risk that could be avoided by closing restaurants completely. It's a complicated issue I'm not confident claiming either way.
The thing that has to be done is to give all essential workers hazard pay, benefits, and every possible advantage to reduce their risk. If someone is labeled essential then they should be treated like it. Right now we're not even treating healthcare workers like they're essential.