If you look at the photo you can see 4 switches. I want to add another one so that it's a master switch which can turn all of them off.

After looking online I see that there are things called smart switches which can also respond to voice commands.

What's the best and simplest solution for my problem?

I am planning to put Shelly devices behind all my dumb light switches, however, I plan to put. a 2 channel switch in my bedside table, one will control my bedside table and the other ideally when pressed will turn off all the lights off in the house. If I put the 2 channel shelly behind here, and programme the second channel to turn the all the other shelly connected lights off, would this work?

i have the sifely bluetooth /wifi gateway that we use with sifely locks. does anyone know if these devices will pass other data beside lock stuff. we have a small motel and looking for a way to 1. allow a panic text (from a bluetooth) to go through the gateway and then 2 also be able to triangulate to a position where an employee might be. they are always on their own and we would like to be able to get help to them immediately if needed. thanks for any help and thoughts