Thanks and yes I understand all that. But I want to know about a clean install for a USB thumb drive.
I agree with the previous posts about doing an Erase All Content and Settings. The SSV is deeply verified every boot and if it has one byte wrong the Mac will not boot. Have you got a particular problem you want to solve?
If you are determined to reinstall from the bootable USB, shut the machine down, plug in the USB. Reboot holding the power button down until you see “Loading startup options” then release. Then select the bootable USB and ‘continue’. The installer will launch. Quit the Installer and launch Disk Utility, erase the ‘Macintosh HD’ volume pair, create a new APFS volume, quit DU launch the installer, and point it at the volume you created. Do not erase the whole drive or you may delete the hidden volumes and the Mac will not boot. (You would need a second mac and Apple Configurator to restore).
After the installation finishes Setup Assistant will launch and you will have the opportunity to migrate in from your -Data volume backup, or proceed to set up from scratch, depending what you mean by “Clean Install”.
If you don't want to erase the Volume Pair you could just run the installer on top of existing. This will leave your -Data volume, so may not be a Clean Install to you.
You could do all the above equally well booted from Recovery, you don't need a bootable USB unless you want to install an older OS version.
PS Stricter ownership and security checks mean there are more things to go wrong doing these kind of operations on Silicon Macs compared to Intel, all avoided by Erase all Content and settings, and then restoring the -Data volume from backup with Migration Assistant, or proceeding to setup from scratch.