No, it doesn't need to lock from the outside. I never said lock from the outside. I saw a product like this recently and can't find it. It was like a long strap that you wrapped around the deadbolt lock and the handle from the inside. But now I can't find it on Amazon at all. So there's at least one

Here is another one I just found, but it's not portable

https://www.amazon.com/Arc-Link-Products-Secure-Brass/dp/B00N95IQQS/