If it has a nest to feed then the baby birds might starve
Also it might get violent during mating season if it is male for some wild bird species
Also if you have other pet birds they might get diseases from it
Also it might be illegal to keep as a pet and not let it leave your house
You could put a bird house outside your house for it
You could contact some group than manages wild life if it is injured
I was thinking if someone put a door that could only be opened up from inside a house inside a bird house attached to a wall they could open it up and let a bird come inside their house without letting animals they do not want to come in through that hole
They could leave a second exit for the bird to go outside any time it wants to
But if you let the bird inside your house from time to time I do not know how you would let it leave your house
Might not be legal