First, I don’t think it’s a good idea for you to let him outside. He may scamper up a tree and not come back down because he’s too frightened. We never recommend allowing them outside without a cage until they are prepared and ready to be released.
How old is Orville? The fact that he’s frightened should tell you that he’s not prepared for a life in the trees yet. Are you familiar with the slow release method? Here’s a link that will explain it.
https://thesquirrelboard.com/forums/...-How-to-Sticky
Singleton squirrels do better if they are released at an older age...in fact all squirrels do IMO.
The animal shelter will not know what to do with him and would probably euthanize him. It may not be easy to find a rehabilitator that will release for you but I’d definitely go that route. Reach out to Mary Cummins at Animal Advocates 323-651-1336. She’s in the Los Angeles area and may be able to help or direct you to someone who can.
Please don’t let Orville outside anymore, he may take off and you’ll never see him again. That is not the way for him to be introduced to a life in the trees.