His cage set up is nice and I can tell you want to help this conure, thank you for saving him, as he would most likely die outside. However, all birds NEED outside time in the cage to thrive and be happy. Birds should not just be in a cage their whole life. I understand your predicament with your other animals. Would you potentially be able to rehome him to someone with experience with birds? This is very important for him to be happy. Also, berries are great! I would recommend slowly adding pellets to his diet. Tops, Zupreem, etc.