I hope that iOS 13 brings a Files app update that will add direct access to file shares. Until then, I will use a utility that I found today: FE File Explorer. It is a clean and polished file explorer that connects to Apple and Windows file shares, as well as some cloud services. It is a good image player, audio player, and video player as well. The Pro version integrates with the Files app as a data provider, too. I am impressed.