Downward pushups and dips do target the lower chest but they put significant pressure on shoulders and forearms. Are there exercises (raw or equipment-aided) that almost totally focus on the lower chest?
1 Answer
The pectoral (chest) muscles are shoulder muscles. They cross the shoulder joint and act to draw the arms towards the chest. So you can't focus on the chest muscles without putting pressure on the shoulders.
If you mean that you want to avoid training the deltoids (sometimes referred to as the shoulder muscles), then flies would be the usual choice for isolating the pectorals. E.g. Pec-deck fly, dumbbell fly