This only works if the system has fully booted up. But, for the original situation which I described in the opening post, it does not work. I say that because I am in the same situation now, and typing AltG+7 does not give a hyphen. Instead, it results in {.
It seems now I’ll have to wait until the next upgrade, and then, as I did last time, rely on using the up arrow to run the upgrade command.