Why won't my iMac boot? (com.apple.displaypolicyd exited with abnormal code: 1)
Let’s start with the basics and permanently enable verbose mode for booting (you can always turn it off later). Boot into Safe Mode (or single-user mode, either should work) and run the following in Terminal:
$ sudo nvram boot-args=&quot;-v&quot;

Then reboot. As you are booting, I recommend using your iPhone to take a slow-mo video of the screen so you can capture the boot text. If you can then put together some screencaps of full screens of text and share them here, we can try to see if we can catch a log of the failure sequence.
UPDATE:
From your screenshots I am starting to suspect GPU involvement. Try booting with the following and see if you get different output:
$ sudo nvram boot-args=&quot;-v panic_on_display_hang panic_on_gpu_hang&quot;

Also can you boot into safe mode and check /Library/Logs/DiagnosticReports for anything involving displaypolicyd?