Problem on install …

Hi everyone,

I’m attempting to install MacOS Sequoia on my 2013 Mac Pro. This may be a dumb idea but figured I’d try. So I got everything installed on a flash drive and I’ve attempted to restart my system and boot from the drive. Every time I go to install Sequoia on my flash drive, I get to the place where I can choose the disk, however only my main HD is accessible, the flash drive is greyed out and when i attempt to select it, it tells me the drive is locked.

What am I doing wrong here?

Thanks for your assistance!!