Perhaps the fact that the stable build for flame has been discontinued from the instructions is playing a part in this. I provided a link (from memory) for the stable builds at the top of this thread but this source is no longer linked to the install page.
The first consideration in the manual install, dev build, https://doc.e.foundation/devices/flame/install is to ensure
Before following these instructions please ensure that the device is on the latest Android 13 firmware.
Pixels are relatively easy to upgrade https://developers.google.com/android/images. Please read the options there carefully. You might consider using Android Flash Tool, https://flash.android.com/welcome.