A virus usually encodes for, and definitely utilizes, many processes of living things.
Part of the breakdown here is recognizing independent life requiring only a nutrient and energy source, and various consortia (e.g. can you say that a mitochondrion is alive without the host cell, and vice versa).
Basically, as mentioned by another commenter, the fact that "life" started out as a Platonic ideal that's being sussed out.
I'd say just change it to an adjective entirely and don't bother with a categorical noun.
"nutrient and energy source" is an interesting perspective: we certainly can't live off radiation (or heat, or electricity, or whatever one might consider as direct energy input) plus all the atoms contained in a lifetime worth of food arranged in simple monogamous molecules. We are no less dependent on other organisms arranging atoms into molecules our bodies can use as fuel and building blocks than a virus is dependent on a host cell for reproduction. I suppose that we can't really want a definition of life that excludes everything that isn't a plant?
As you state, the carbohydrates, fats, and proteins in our food sources function as energy sources. Photons are great for plants, but comparatively high-energy chemical bonds are fine, too.
Part of the breakdown here is recognizing independent life requiring only a nutrient and energy source, and various consortia (e.g. can you say that a mitochondrion is alive without the host cell, and vice versa).
Basically, as mentioned by another commenter, the fact that "life" started out as a Platonic ideal that's being sussed out.
I'd say just change it to an adjective entirely and don't bother with a categorical noun.