If you just want to use it in manual mode, as against programmed CNC style control, but at a safe distance then this is quite an easy thing to do.
Physically on the remote you need to decide whether you want to use one pulse encoder per axis or switch a single encoder to which axis you want. Personally I much prefer the idea of one encoder for each axis, this is more intuitive because it mimics the manual controls on the machine.
Then you need to process the signals from the encoders and convert them into suitable output for the steppers. All that you need is readily available in whatever budget range you have available. Most can be done with user friendly microprocessor boards like the Arduino and Pi. I have done very similar things to your requirements with an Arduino Mega, although without the danger aspect of your task.
The Arduino Mega can be used directly with the encoders to decipher the signals but I prefer to use dedicated quadrature chips between the encoders and the Arduino. This is more reliable and simplifies the programme coding.
There a number of off the shelf stepper driver boards which can be driven by the Arduino and drive the steppers, it is just a question of getting a driver board which has the capacity to match your steppers.
Connecting all that up is pretty simple but then you have to write some code to tell the Arduino how to react, that is probably a stumbling block for many people but this is a pretty simple application and I am sure that you will have people around you who could handle both the connecting up and the programming.
I'll try to remember to look up the spec of the quadrature decoder chips that I use. There are different types and some are much more suitable than others for this task.
https://store.arduino.cc/arduino-mega-2560-rev3