How do we transfer to another Blender file. Copy paste won't work. This grop nodes is to make textures random. Group nodes
Bonus question: How do we make the wires straight?
For the straight wires you go to edit, preferences, then under themes go to the node editor, scroll down and turn down the zero the option called noddle curving.
To transfer things between files, you can go to file and then append. Navigate to your .blender file and go inside it by double clicking. You'll see folders of the data blocks of your blender file and you can go to any folder, including materials and node groups and append them to the file you're working con.