CircuitPython 8.0.0 introduces support for environment variables. Environment variables are commonly used to store “secrets” such as Wi-Fi passwords and API keys. This method does not make them secure. It only separates them from the code.
CircuitPython uses a file called settings.toml at the drive root (no folder) as the environment. User code can access the values from the file using os.getenv(). It is recommended to save any values used repeatedly in a variable because os.getenv() will parse the settings.toml file contents on every access.