How to develop a program that uses another program ?

I want to develop a program based on

https://github.com/alacritty/alacritty

and is simillar to MobaXTerm

Which is basically taking terminal and adding features around it like windowing, sessions and more.

I know I have to deal with OpenGL contexts: alacritty uses opengl and glut and I want to capture the context and display it, using other languages such as java or python instead of rust