Will a breakfast consisting only of bananas and green apples be good or bad for health? Is it recommended? Plus soya milk

It Depends. As with all things in life; it depends. Fructose with fiber is good and you also need protein to modulate your blood sugar spike which is bound to happen with a fruit only breakfast. I recommend doing a "smoothie" with a high grade medical food (pea and/or rice protein) along with your fruit. You will be satisfied and keep your blood glucose stable. To your best health!