How do I handle iPhone 14 Pro with a completely shattered screen?

If it is only the screen damaged, you could have the screen replaced by Apple. However, if there is damage to the case you would need to replace the device. If you wish to contact Apple about service, see this. Genius Bar Reservation and Apple Support Options - Apple

Understand that the cost to replace the screen on an iPhone out of warranty may not be cost effective on an older phone like that.

You will either need a new screen or a new phone.

It will be difficult to back up from a PC or Mac, as you will be asked to enter your password (on your iPhone) when connecting. Hopefully you already have an iCloud Backup - otherwise, a lot of your stuff is hopefully synced up with iCloud, so you can load it onto a new device.