Raspberry Pi 4 modify cmdline.txt no boot .Can I start USB disk?
the current PI4 bootloader only supports booting from an SD card, booting from usb appears to be wip.
Check the Raspberry forums.
Has anyone got volumio to boot from USB yet?
USB boot on the Pi isn’t a priority for the dev team - there are a few post around detailing why, such as this one Boot from USB or Network from backup - #8 by robcee
As per the exact answer to your question, yes but it’s not something ready for primetime, and just something quick I whipped up.
PS: Welcome to the forum 