yes. USB2.0
FWIW, on my vanilla Pi3+ it takes about 11 seconds to get to the splash screen and another 15 to get to the gui using just an SD card.
Using an SD card to boot with the OS on a USB (another SD in a card reader) was slighly quicker - 24 seconds overall.
Booting from the USB card reader with no SD card in the Pi’s card slot took 58 seconds to the splash screen but then only 8.6 seconds more to get to the gui.