Review on USB to iPhone Adapter - Plusysee iPad USB 3.0 Female OTG Adapter with Charging Port - Plug & Play USB Camera Adapter for iPhone/iPad - Support Camera, Card Reader, USB Flash Drive - iPhone USB Adapter by Greg Bellman

Worked better and faster than I thought. After reading reviews of similar USB adapters, I expected trouble. Essentially, I just plugged it into my iPad, plugged in a USB drive, and browsed the contents in the iOS Files app. Tested with PDF, MPEG and JPEG. Everything is open and working great. I expect to use this a lot for movies etc when traveling. It feels solid enough and the power pass-through port is great for charging an iPad or iPhone for extended use.