Lightning to usb

For an iPad Pro with Lightning connector, you’ll require an Apple Lightning to USB3 Camera Adapter:

https://store.apple.com/uk/xc/product/MK0W2ZM/A

To provide sufficient power for the USB drive, you’ll need to connect a Power Adapter (charger) rated at least 12W to the auxiliary Lightning port of the Camera Adapter. The iPad, on its own, except for very low power devices, cannot supply adequate power for connected USB storage devices. The Power Adapter supplied with your iPad, with the appropriate cable, is likely to be adequate.

For an iPad Pro with a USB-C connector, you’ll need to connect your iPad and the USB Flash Drive to a powered USB hub.

In all cases, your USB storage must have a single data partition - and be formatted as FAT32, exFAT or APFS. iPad cannot read multi-partition devices, or proprietary device formats (such as NTFS).

There are many products on the market. This is an example:--> https://shop.westerndigital.com/en-us/products/usb-flash-drives/sandisk-ixpand-usb-3-0#SDIX30C-032G-AN6NN

Regards

Giulio