Buenas noches, si alguien le ocurre este error al tratar de levantar el servidor y está usando Windows para desarrollar con Python, dos cosas, la primera es que hay que cambiarse de SO para desarrollar, y la segunda es que se soluciona muy fácil:

Error traceback: Usage: flask run [OPTIONS] Try 'flask run --help' for help.

Error: While importing 'app', an ImportError was raised:

Traceback (most recent call last): File "D:\REPOS\Flask-Learning-Advanced\venv\lib\site-packages\flask\cli.py", line 218, in locate_app import(module_name) File "D:\REPOS\Flask-Learning-Advanced\app.py", line 11, in db = SQLAlchemy(app) File "D:\REPOS\Flask-Learning-Advanced\venv\lib\site-packages\flask_sqlalchemy\extension.py", line 219, in init self.init_app(app) File "D:\REPOS\Flask-Learning-Advanced\venv\lib\site-packages\flask_sqlalchemy\extension.py", line 326, in init_app engines[key] = self._make_engine(key, options, app)
File "D:\REPOS\Flask-Learning-Advanced\venv\lib\site-packages\flask_sqlalchemy\extension.py", line 614, in _make_engine return sa.engine_from_config(options, prefix="")
File "D:\REPOS\Flask-Learning-Advanced\venv\lib\site-packages\sqlalchemy\engine\create.py", line 813, in engine_from_config return create_engine(url, **options) File "", line 2, in create_engine File "D:\REPOS\Flask-Learning-Advanced\venv\lib\site-packages\sqlalchemy\util\deprecations.py", line 277, in warned return fn(*args, **kwargs) # type: ignore[no-any-return] File "D:\REPOS\Flask-Learning-Advanced\venv\lib\site-packages\sqlalchemy\engine\create.py", line 600, in create_engine dbapi = dbapi_meth(**dbapi_args) File "D:\REPOS\Flask-Learning-Advanced\venv\lib\site-packages\sqlalchemy\dialects\postgresql\psycopg2.py", line 667, in import_dbapi import psycopg2 ModuleNotFoundError: No module named 'psycopg2'

Solución: Ejecutar el comando 'pip install psycopg2' dentro del entorno virtual. O agregar psycopg2 a su archivo requirements.txt y ejecutar el comando 'pip install -r requirements.txt'