Deploy app.py and requirements.txt to Raspbian.
Login to Raspbian and set up the Python environment (You need python3-venv to use venv).
$ python3 -m venv venv
$ source venv/bin/activate
$ pip install -r requirements.txt
Enable serial communication in raspi-config.
Run the app.py script under the venv environment.
(venv) $ python app.py
Deploy app.js and package.json to PC.
Install node-picmd using npm.
$ npm install
Run the app.js.
$ node app.js