Unfortunately, that's a tough one to answer. Since it needs to be decrypted, the only routes right now are: 1) download it on a device and then decrypt it, 2) download it from extremely sketchy, illegal sites, or 3) for bug bounty cases, hope they give you an IPA that you can just use. Given the primary use case is making life better for bug bounty hunters, #1 and #3 will cover the vast majority of uses initially, but I really think a better solution is needed down the road.