I'd like to lock my Mac, that is, require a password before any input.
This is normal.
What's different, though, is that I'd like to be able to show the exact same output as if the screen was not locked.
Let's say, for a trivial example, that I was watching a the output of a long-running process.
If I could do this, I could then lock the mac, but still be able to see the output. If I wanted to do anything other than watch the output, though, I'd need to unlock the Mac.
Note: I have done some cursory research on this.
But it's pretty hard to find this in a search engine.
Even on the StackExchange, most of the questions are about how to lock the screen without putting the Mac to sleep or activating a screen saver:
How do I lock my mac without the screen going dark or going to the screensaver?
Lock Mac without turning off the screen
For those sorts of things, control+⌘+Q works just fine. I'm asking about something different.
Update: Looks like this guy asked something similar: Transparent locked screen
And the best Invisible Screen Saver for multiple monitors is Transparent by Monkey Bread Software.
https://www.monkeybreadsoftware.de/Software/Transparent.shtml
Now I just need to find out how to lock the screen and go to that screensaver in one stroke.