They aren't, though specifically for groceries, it's somewhat-less relevant for the US than Canada, because we produce a wider variety of food domestically.

There are some important things that we do import, which have been discussed on here, like out-of-season fruits and vegetables.

kagis

These guys highlight several fields:

https://www.eatingwell.com/foods-impacted-by-new-tariffs-11712453

Tropical Produce

the US consumes more than it has tropical regions to grow tropical foods in.

Seafood
Coffee
Olive Oil, which we mostly get from Europe. "The U.S. produces only 2% of the olive oil that it consumes"
Chocolate
Nuts (though IIRC we're a major producer of some important nuts, like almonds and peanuts).

Also, the foods that we're especially competitive in tend to be bulk, low-value stuff, grains and such, which is the staple stuff that you'd really need if prices went up. We tend to import stuff like luxury food from Europe, which is nice but something that one could live without if one's budget was tight.

One impact will come from fertilizer, which we import a lot of; that'll drive up our cost of production of food.

The fact that we're a major exporter of food is actually a major reason why you'd expect the agriculture industry to be unhappy with Trump, though agricultural states tended to vote for him. American agriculture is, by-and-large, globally-competitive. If it were uncompetitive, then tariffs might benefit it, providing useful protection from competition by forcing American consumers to buy it rather than more-competitive foreign products. And despite the lack of benefit, the agriculture industry likely does get hit by countertariffs.

The industries that will tend to benefit from tariffs are those where America isn't very globally-competitive in 2025, maybe low-skill, labor-intensive manufacturing, and that's where consumers are going to take a price hit from taxation. Clothing prices, for example. We're not very good at hand-producing clothing. Tariffs will cause those industries to be subsidized by transferring money from the industries that we're better at.