Agree with
@007p mostly. The answer is no, with caveats.
You can pick up something like this for as little as $25 that has a normal usb connection on side and lightning on the other and functions as a USB drive. Or you can get a lightning to USB OTG adapter for $5-6 but, without the use of an app, the OS itself the OS can generally only see the DCIM folder (where photos are kept by cameras).
I too expect this gap to be filled by the makers of some of these device with storage provider plugins in Files. I'm rather more hopeful that some of these will be ready on day 1 or thereabouts though, given manufactures will have had the beta in hand for a couple of months at that point. Probably the high end manufacturers and devices will see support first.