Flutter windows: Struggling to setup file association - Retrieve filepath from custom file on open

Question

I am building flutter windows desktop app and have a custom project file .myproj that can be saved from the application and later reopened by double clicking on the file in explorer.

The issue is that I need to retrieve the filepath of the file on app open, however there don't seem to be any documentation to achieve this.

After some research, I discovered that this could be achieved via method channel and one will have to write some c++ code to get the filepath argument.

Not familiar with c++. Can anyone help with a resource or codeblock to help me achieve this?