Now I have a flask server deployed on a virtual machine, so that my colleague can use the AMI without deploying a python interpreter, on the flask server my python script has the ability to open the local file box, but it is indeed the local file box on the virtual machine, how can I make the python script open the client’s local file box
Short answer: You cannot.
Longer answer: You can potentially do this by using some remote command to the OS of your user, but this may be unsafe, not possible or very very difficult to accomplish.
You really should use the local URL method for this.
What Operating systems are you running?
If on Windows, does your studio have a Active Directory Domain with Group Policies?
It would be pretty easy for your sysadmin to add this setup in a policy and push it out to your workstations.
Same goes for Linux, pretty easy to push this out.