To import WordPress users to Yii2 just do this:
- import all the data, that you need, to the User table in your database.
- You can have there Yii2 or/and WordPress hashes for passwords
- Replace vendor/yiisoft/yii2/base/Security.php with the file from this repo.
What the file does: instead of exception of invalid hash it starts to use a wordpress functions for another one password validation. It all is still secure. Enjoy.