For your bird’s health, you need to keep him in his cage when you are not there to supervise him. While this chewing may or may not bother you, it can be dangerous to him, especially if this is a new build. Woods for construction are treated for termites and other things before it is installed. Even if the paint is safe, the stain probably is not and again, you have no way to know what chemicals it has been soaked in. The sprays almost never work for birds. You can try it but I doubt it will work. And there is the concern that he will move to something else that could injure or kill him. I know you like leaving him out, but he can be perfectly happy in his cage when nobody can watch him. Get him a larger cage if needed and make sure you have plenty of toys for him. Many bird toys are made with very hard woods and this is harder to chew, which means the bird gets tired of the toy. So look for some toys he can more easily destroy and he may get more interested in them again. He won’t be happy at first but he will adjust. He doesn’t know what will hurt him so it is your responsibility to protect him and the cage is there for his protection.
Thank you for asking Lafeber,