This open source Raspberry Pi HAT adds a microSD Express card reader for PCIe SSD-like speed (read speed anyway, write is less impressive). MicroSD Express cards are expensive & rare though, so this board won't be mass produced, but you can make your own from the designs. https://www.cnx-software.com/2025/07/28/raspberry-pi-5-gets-a-microsd-express-hat/#RaspberryPi#MicroSDExpress