This is a little fancy, but I have a custom Lock Screen for my phone that’s just a pink background that says “This phone is lost. Please contact xxx”. And I have a custom focus called “Lock Screen” that I can set from another device (i.e, my Apple Watch) that will sync the focus to the phone. And I have an automation that runs on the phone that when the “Lock Screen” focus is set it changes the Lock Screen wallpaper to that custom image, locks the phone (if it is unlocked), turns on wifi and BT, turns off airplane mode, turns on low power mode, and turns on cellular data, hopefully before someone who finds it tries to turn off the radios, etc.
It’s an option on my installation of Big Sur.
Again, Big Sur: Security & Privacy → General → Show a message when the screen is locked.
But it doesn’t work (for me). I had forgotten about this feature, and went to set it after your post. (Thank you.) It was already set, be it has not appeared on my locked screen for a long time, if ever (which is why I had forgotten it).
How frustrating. If I remember correctly, Big Sur displayed the message in relatively small print immediately above (or maybe below) the row of icons representing users to log in as.
On Sonoma, it’s above the cluster of bubbles representing users:
The print is still too small, but it’s there.
For iOS, I found an article with several methods, but all involve either editing the wallpaper image or installing an app with a widget you can add.
Apple should create their own text-only widget so this can be done without third-party software.
I hate it when I make misleading statements. Let me try again. “I have not seen it on my locked screen for a long time.”
And that’s where it is. Well, it’s actually just above the two icons for Cancel and Switch User, but it’s that part of the screen.
My MBA is connected to an external display and is almost always closed. When I’m ready to unlock the screen (because I’m already logged in), I press a modifier key to alert the Mac that something is about to happen, then type my password. (My recollection is that I started this behavior because the Mac would ignore the first character or two of my password if I simply started typing.) Often I finish typing before the external display comes on, so I don’t see the locked screen.
There is a dumb workaround: bake the text into your lock screen image.
What temperature?
(I’ll see myself out)