You could potentially shotcrete (spray it with concrete to reinforce) the wall after the robotic excavator is done if you’re concerned about stability. I can’t speak to whether you can highly automate this as well, but it seems possible with current state robotics with human operators.
https://en.wikipedia.org/wiki/Shotcrete
https://www.geostabilization.com/technology/shotcrete-robot/
https://dawinvehicles.en.made-in-china.com/product/jBMnaOKdL...