Indeed for T_3.2 noted in OP - an external HOST Shield would be required.
The link from KurtE points to Working - work in progress - that allows file access using T_3.6 USB Host connection. If anyone did it before it was not shared until that thread was started and it was developed in coordination with the soon to be released Teensy 4.0 that has similar USB Host support.
If you get a T_3.6 {And the USB connector soldered to the T_3.6} and want to see USB Host access to USB Data Stick - post on that thread and we can help you get the needed libraries to compile a working sketch. As noted it is a work in progress - but have made it work here as have others on that thread. That will also work when the Teensy 4 ships - but the T_3.6 will be easier to wire up given the through hole pins.