Is it possible restart Mac from 2nd monitor only without mouse? My Mac has an issue where sometimes the primary monitor won't wake up, but the Mac thinks it is connected. So In such cases, I only see my secondary (much smaller) monitor.

Typically I cannot find the mouse cursor so I'm left with a monitor but no way to do anything. Restarting fixes it but I end up having to force-power-down by holding the MacMini power button then restarting... is there a way I can access the Restart menu option in this scenario instead?
You can set a key command to it, same as any menu item, though you're flying blind. If any app wants you to confirm save/discard you may not see it.

Whilst I'm aware this is really an XY Problem I've answered the Y ;)