I finally manage to deploy with a docker image and App. Engine with this DockerFile:
# Create working directory
WORKDIR /app
# Copy requirements. From source, to destination.
COPY requirements.txt ./requirements.txt
# Install dependencies
RUN pip3 install -r requirements.txt
# Expose port
EXPOSE 8080
# copying all files over. From source, to destination.
COPY . /app
#Run app
CMD streamlit run --server.port 8080 --server.enableCORS false app.py
Check this video from Jesse E. Agbe