To import pictures from a camera SD Card, you simply require a USB-C to SD Card Reader - such as this one from Apple:
https://store.apple.com/uk/xc/product/MUFG2ZM/A
If instead you wish to use a USB Flash Drive, you’ll need to consider its USB connection. If the drive uses the older (larger, rectangular) USB Type-A connector - or a USB-C connector, you may need need to consider an appropriate Adapter or USB Hub.
Anker manufactures many different models of USB hub, some being suitable for iPad - and some being totally unsuitable. Some may incorporate an SD or microSD Card Reader, others not. When looking for a suitable USB Hub, check the specifications to verify that the hub is Made for iPad (“MFI”) - or otherwise specifically states that it is compatible with iPad.
There are many third-party USB Hubs that have a USB-C connection for iPad plus a USB-C PD (Power Delivery) pass-through power connector to which you can connect your USB-C Power Adapter - along with the hub itself incorporating a combination of additional USB-C ports, USB 2.0/3.1 Type-A ports, Ethernet LAN, HDMI, VGA, SD and microSD card-readers.
As alternatives to Anker, perhaps consider Kingston, Hyperdrive and Satechi - although there are many others from which to choose. A Google Search for USB-C Hubs compatible with iPad will find a number of articles and recommendations.
Speaking of personal experience, the Kingston Nucleum has proven itself to be particularly flexible for connection USB storage devices - featuring twin USB3.1 Type-A, downstream USB-C and SD/microSD card slots, HDMI, plus a power pass-through USB-C port that can accept +45W from a suitable USB power source.