Is the Minecraft folder structure the same on all platforms?

Short answer: Yes, the contents of the folder will be the same

Long answer: Yes, however the location differs. If you're using python, you can use the sys.platform() function to get that data. Typically, the default locations are:

• Windows: %appdata%/.minecraft
• MacOS (darwin): $HOME/Library/Application Support/minecraft
• Linux: $HOME/.minecraft

It might also be useful to allow the user to choose a custom .minecraft path if they're using a custom launcher.

Edit: According to this stackoverflow question, you should try to use platform.system() for a more consistent output