iPhone stuck on "Preparing Update" for hours

No, it's not.

Are you transferring the data from an older iPhone? If that's the case, other users have had the same issue : iOS does not update. The solution is to set up the new iPhone as a "new iPhone", i.e. without transferring the data, update iOS, erase the iPhone and then start the transfer again.

iOS 17.4 took less than 1 hour to update on my iPhone. Your screenshot shows you have a strong Wi-Fi signal. If no other devices are using the Wi-Fi excessively, we can drop this potential cause.

You could try to restart the iPhone. Otherwise, try using a Mac or PC Windows to do the update.

The best way and supposed to be fast less than 30min its having the iphone pluged straight to the outlet with its original cable and also having a good strong signal of the wifi device that you are using. if it hasn’t download completely you can stop it check the memory of the device and the strengh of the wifi connection.

The signal is strong (3 Wi-Fi bars), the throughput of your connection maybe not so much as you indicate. It is indeed possible that this is causing the issue. Leave the iPhone update overnight.

iOS updates are usually about 4 GB big. Android updates are between 500 MB (or less) and 1 GB (rarely), so a lot smaller.