Encountered an alternative way to get possibly usable low-light photos with the Moto G4 (other than using manual controls as described in previous post): use the Night Camera app.
Even though it is no longer supported, it is the best I've found at reducing noise in low light. It does this by taking 8 photos in rapid succession to analyze and form a single photo.
Obviously, it is kind of slow and won't work well when there's any movement, and some detail is lost. But it is another possible tool to use to salvage the G4's camera in low light.