Along the front foundation there are these bushes that are looking quite sorry. I'm not sure what they are, I believe they may be some sort of boxwood shrub?

The shrubs are very sparse and aren't looking very good. I'd like to either tend to these to get them to fill in, or find a replacement that will fill in better. I'm not sure if I should try to prune them at all, or add fertilizer, or???

They get a little bit of sun mid-day, but not much. Not sure what soil prep has ever been done, last owners did not do much of anything landscaping wise.

Here they are:

What you have looks like it's going to be a forever trimming task every year.
Pull them out after a decent rain loosens the soil then replant them where they'll look better.
Then you have a wide opportunity of choices what to plant
in that spot.
While you have the shrubs out, you might even want to redesign the front steps in brick and incorporate them into a lower planter across the front of the foundation no higher than your foundation vents.
Imagine a pretty brick planter filled with cascades of flowers (of course you'll have to water them)
Just a thought.