My dad had one of these. It made it clear that he wanted his girlfriend to make all these decisions on his behalf.

Despite this document, when he was hospitalized with a stroke, the hospital wouldn't do a thing unless my sister and I signed off on it.

Because we were family and his girlfriend wasn't.

Had she been his wife, it would have been different.

The point is that even if you have all of the right documents in place, you can still get resistance and pushback.