Monterey 12.3 doesn't install on an external SSD
I'm on a 2019 16" MBP. I downloaded the App Store Monterey 12.3 installer. I ran it onto a bare 1 TB external SSD. It seemed to load onto the drive correctly, and at the completion the system rebooted. Normally it them proceeds with the installation. Instead, the system booted into the internal drive. The drive appears to have the system on it. I tried booting with the Option key, but it doesn't see the external drive. However, once booted into internal, I can go to Startup Disk, and it sees the external as a startup volume.
I can select it, but when I try to restart I get this error message.
I've tried this a few times on a couple of drives with the same result. This is pretty ridiculous, extremely frustrating, and a complete waste of my time.
If anyone has any idea what the problem might be, or how it can be remedied I'd very much appreciate some help.
Thank you for any assistance.