What I want is not that the screen turns off when the lock timer times out,
This might be a problem, I don’t think you can have both behaviors at the same time.
but that I can push ‘lock’ or a key combination and have the system lock and the screen turn off immediately. The new ‘when locked, turn off screen’ setting should help with this, but setting it too low will presumably make it hard to unlock.
Setting it to 0 will function just how you described, it won’t make unlocking it harder. When the password prompt is open, it blocks the screen off behavior.
For running backups, ‘after a period of inactivity’ could help.
It should work for your case of creating backups when idle. inactivity = no user input or program sending block signal = most likely idle.
It still seems like the removal of a useful feature.
Sure, but for your case I don’t believe you actually need it.