Why is it taking way too long to update

Try this https://support.apple.com/en-gb/HT201435

Connect the phone to the charging circuit, and charge to at least 50%. Then leave it attached to the charging circuit as you attempt the update. Also, turn off the Automatic update option.

This is a security update, so it will take some time for patches.

PS. Make sure to plug your iPhone to charger 😜