A face covering is, by definition, something that covers your face. A shield covers your face so should be accepted as conforming to the government paranoia demands.
if masks are hard, try what I have - a flouncy scarf that is a continuous circle. I can tighten it to my face when needed then you can just loosen it after
I wore a face shield yesterday and was allowed on the bus. I will continue to wear it in shops but I will also carry a mask in my handbag in case. Since I live in a place where social distancing in shops and streets is pretty easy, I feel this is enough protection for me and, as I sat in a cafe yesterday and had a coffee with friends with it off, it all seems a bit something and nothing to me.
OG, a shield is different from what most folk would describe as a face covering. The face covering is in contact with the nose and mouth whilst the shield is not.