Hi James!
I’m sorry for the delay in response!
Yes, USBHostHandle
is for connecting a USB flash drive into the Daisy’s USB port and reading files.
Here’s the class docs on that: libDaisy: daisy::USBHostHandle Class Reference
Since the Daisy is a class compliant MIDI device over USB, it’s not possible for devices also looking for a host (like a KeyStep) to send MIDI directly to it via USB. So as of now, you can only send MIDI from the KeyStep to the Daisy via TRS MIDI. That being said, USB host functionality is a feature that’s planned for the future!