There are a lot of ways to do this. You could:
- Use a custom authentication driver on your Laravel app to use WordPress database. Hampel's package does this.
- Use a custom authentication provider to authenticate WordPress users. Laravel WP User package can do this, and it also support REST API.
- Override Laravel's hashing to make WordPress compatible password hashes using Laravel WP Password package. You can read more about this here.
- Replace WordPress's built-in authentication.
- Use Auth0.
There are probably still more ways to do this.