… I think the lockup may only be that it is killing my USB (both keyboard and mouse are USB) but the only way out of it is a hard reset. No keyboard/mouse leaves no other options that I know of.
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Remote control access from another computer on your local network
I have a computer here that sometimes ignores keyboard and mouse upon first reboot after an OS software update. My work-around is to access the unresponsive computer from another laptop in the same room. I use basic remote access software, which you can pre-install on both computers, ready for future use.
I use the remote access to complete the normal login and start-up process, then instruct the troubled computer to fully shut down. Subsequent restart allows mouse and keyboard to again function, and it continues to so so for many weeks. Until another software update retriggers the problem again.
In your case, if remote access works, you can complete the document save (if that is what you want to do) and then tell Windows it restart,
A quick experiment with plugging in a second keyboard and mouse might allow you access. Back in the day I would use an old PS/2 style keyboard and mouse to get around a hung USB driver. Those connectors are long gone form modern PC motherboards.