Practice from boards on a Pinterest account that authorizes this app. Pins are read when you open a board and when a session starts. They are not copied into the library and they are not published.
App credentials
This machine has no Pinterest app id and secret. Register an app, set PINTEREST_APP_ID and PINTEREST_APP_SECRET, and register this redirect URI:
https://desenho.teomoura.com/api/pinterest/callback
Until then, import files from the library.