Mua Satechi USB-C Slim Dock for 24" iMac (with slot for M.2 NVMe ...
These are USB SD card reader with a slot for standard SD cards.
Amazon.co.jp: KODLIX Mini PC N100 16GB DDR4 512GB SSD 4C/4T Max ...
How to Boot Windows from SD Card [A Step-by-Step Guide] ... If this slot is broken, you buy an SD card reader and then connect the SD card to the USB slot.