I always lock my computer when I'm away from it (Win+ L). Would this be able to detect that?

It's useful to still have Focus mode on when I'm not using Chrome otherwise though (I mostly work in Excel).

I think option 2 means the user is least likely to be distracted and move straight into focused work, as opposed to potentially delaying the work focus for another few minutes with option 1.

Option 4 would be effective but would be preferable with a warning (essentially option 2).

I don't know how option 3 would work.