Yes. The Pi3 could always boot from USB once you enable[1] it. The difference with the Pi4 is that it's initial boot eeprom is now updatable. The first release

Yes. The Pi3 could always boot from USB once you enable[1] it. The difference with the Pi4 is that it's initial boot eeprom is now updatable. The first release didn't include the option for USB booting. It has just recently been added [2]. [1] https://www.raspberrypi.org/documentation/hardware/raspberrypi/bootmodes/msd.md https://www.raspberrypi.org/documentation/hardware/raspberry... [2] https://github.com/raspberrypi/rpi-eeprom/blob/master/firmware/release-notes.md#2020-05-15-add-pieeprom-2020-05-15-beta-with-usb-boot https://github.com/raspberrypi/rpi-eeprom/blob/master/firmwa...