I’m stuck on the login screen

That's good news in the fact the keyboard itself is probably ok, which means you ought to be able to start that Mac in Recovery mode.

To do that, please follow the instructions under How to start up from macOS Recovery in About macOS Recovery on Intel-based Mac computers - Apple Support. Invoking Recovery Mode requires that you press and hold the ⌘ and R keys with two fingers, while turning it on with a third finger, so obviously the keyboard has to work.

• If you can get your Mac to start in Recovery mode, determine if you can perform the rest of the instructions in that document.
• If you are unable to get your Mac to start in Recovery mode, then the ability to continue troubleshooting on your own becomes limited and may not be possible. Perhaps the keyboard really isn't working.

It's possible. Before you draw that conclusion determine if the keyboard responds to anything at all. The simplest method is to press the Caps Lock key. If its green LED does not illuminate, then either the keyboard is defective or the Mac is powered down.

Are you unable to enter your password in that box? Nothing happens when you type?

One more question please, to clarify: You posted your question in the MacBook Pro forum so that's what I assumed you are using.

This is on my Mac Pro

Model designations can be confusing. Your profile indicates you're using an iMac Pro, which is different still. Which one is correct? It may change the answer.