So I followed Inigo's advice, plus a little code I found elsewhere (starting with python on google plus a quick lab)

Create the VM as per here SSH in Run this code

sudo apt-get update
sudo apt-get install git -y
sudo apt-get install python3-setuptools python3-dev build-essential python3-venv -y

curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
# wget as suggested in the docs didn't work for me
sudo python3 get-pip.py
python3 --version
pip3 --version

python3 -m venv env
source env/bin/activate

Sprocket on the right to upload the files

pip install -r requirements.txt
python3 filename.py

Thanks for the comments and tips gang. This has got me moving

Your Flask application should be something like below:

import os

from flask import Flask

app = Flask(__name__)


@app.route("/")
def hello_world():     
    return "Hello World!"


if __name__ == "__main__":
    app.run(debug=True, host="0.0.0.0", port=int(os.environ.get("PORT", 8080)))

See this official documentation for step by step instruction: Deploy a Python service to Cloud Run

There is a plugin called: Cloud Code IDE plugin which makes the test and deployment easy. I am using it for VS code, once the initial setups and permissions are taken care, few clicks, you will be able to run locally, debug and deploy Cloud run services from your local instance.