Mac stuck booting after Monterey

Are you using external hard drive? Some people reported extremely long boot times (30+ minutes). Try to leave your mac booting for an hour, maybe it will boot up. If that's the case, as for temporary solution: let your mac sleep, instead of shutting down, till fix comes out. https://discussions.apple.com/thread/253302798

It seems there’s a problem with USB devices: https://discussions.apple.com/thread/253303875 https://discussions.apple.com/thread/253308334 Try to remove all external peripherals while booting up, including mouse and keyboard.

Another similar issue:

https://www.reddit.com/r/hackintosh/comments/qgcw3z/long_boot_after_monterey_update/ Maybe try to disable bluetooth

I have 2017 iMac 27 retina myself, it boots in 20 seconds, internal SSD.