This is all a matter of my opinion and my own experience. You can do that… but I wouldn’t call this an “emergency stop”.
It really depends on what you want out of the feature in this decision.
Using google voice to interrupt voltage during an emergency is relying on this voice activation feature which is hardly consistent enough or safe enough to use as a substitute for “emergency stopping”.
Furthermore, relying on an outside to process and execute a command over your network is just not swift enough compared to interrupting power via a tried and true emergency stop button/switch, which is why all industrial equipment has them.
I use smart outlets in many areas of my house, such as to control my fan, the automatic litter box, and my lighting… but saying “Alexa” then saying “Turn off the Snapmaker” (then watching a blue circle spin around before a beep then an execution of command at BEST case scenario) is not something id put my safety into. Especially since I frequently have to repeat myself. Even assuming the google assistant is more reliable, its too many unnecessary hands in the pot for the task at hand if you are trying to accomplish a safety mechanism.
You could, if you choose, interrupt main voltage to the power supply just the same with an emergency stop button, but main voltage is not as safe to work with, and I think technically cutting the 24V output would be a little faster since the power supply maintains a little residual voltage. This might be to the benefit of resume task though, since it relies on that residual voltage to kind of mark where your project is before the voltage disappears.
I personally have a comfort level to interrupt main voltage as I work with hard wired switching power supplies frequently, but I don’t think I’d try to extend that to everyone. You could simply use the output cable from the power supply into the button, then back out of the button to the controller and interrupt things cleanly. Interrupting only 1 pin from the power supply would be simple to accomplish inside and you can pass thru the other pins with no ill effect.
I would also like to add that I don’t think the “recovery” command is very reliable in the first place. Actually, I’ve had instances where filament runout recovery executed as power loss recovery for some reason, and I was unable to resume the project regardless. These are firmware quirks that need ironed out yet, but it’s hard to even pinpoint them because things happen at random on you when you are doing things, so it would require a sit down to pinpoint when this occured and why, which may or may not have the dividend of being fixed in the first place.
There is nothing wrong with using your smart outlet to cycle power on the machine, but i wouldnt want to count on that to be my safety. I also don’t find the need to cycle power to my machine very frequently, although some people claim its a requirement between jobs, I don’t agree with that assessment and the only time I find myself restarting is if I try to cancel a job and the cancelling get stuck. I think maybe in some cases people may be missing some start and end gcode to properly set the machine to the correct travel mode and homing.