Aggressive Rescue

I recently rescued this chiweenie from the shelter. He came from a hoarding situation where he lived with a colony of 30+ other dogs and has had little human socialization. I’ve just managed to be able to pet him after a month and a half. He’s come to trust me (slightly) but is still terrified of others. He used to just hide when people were around, but now he’s started barking loudly and getting aggressive (he hasn’t bit anyone yet). I’m trying my best to follow any advice I can find, but it seems like he’s just so riddled with anxiety that everything I try doesn’t work. I live with other people and if they decide I can’t have him because of his aggression, I have to surrender him to the shelter. I don’t want to give up on him yet. What can I do?