How do we know which version of Raspberry Pi 4 we have?

I purchased 3 Antsle Nanos (Pi 4).  I was hoping to see if I could boot them from an attached USB drive instead of the SD card.  I understand that the original Pi 4 couldn't, but the B version could (with Raspberry Pi OS).  How do see what version of the Pi 4 I got?

I believe I saw something or was told that we couldn't boot the Anstle Edgelinux from a USB.  That would be a great feature to have, if it isn't already possible.

Hi dblatt17:

You can find your model here:

cat /proc/cpuinfo

Although this may be possible to boot from USB on the hardware, it has not been implemented on edgeLinux 2.1.0.