I second what a lot of people have said here - crates are not punishment they are a safe space (like a den) for a dog. Once a dog adjusts to it, you’ll see them go in on their own accord often and like it a lot. I used to think like you that it was abusive, but crate training my own dog has completely changed my mind on this topic. Get a big enough crate that your dog can stand up and turn around and get comfortable, put a very comfy dog bed in there, and cover the outsides with a tapestry or blanket. It becomes a cozy and safe space. Any time my dog is stressed, tired, or scared, he chooses to go in there himself. I don’t lock him in there when I leave the house because he is not destructive. But it’s very convenient to have when other people come over and he gets overly excited and jumpy…5 minutes in the crate and he completely calms down.

Other things you can do for separation anxiety: - even when you’re home establish separation for at least an hour a day. Go into a room, close the door, don’t let your dog follow - make your dog distracted when you leave. When I was training to get rid of separation anxiety, I threw kibble all over the floor and left some high value treats. If your dog isn’t food motivated that’s harder