Long time no see!
Here comes a new app called "app_sanic.py" that uses the SANIC framework instead of flask. This app works with both Python3 and PyPy3, but not Python2. Videostreaming is now provided via the UV4L video driver/streaming server. UV4L must be installed separately. The default UV4L stream settings (Port 8080, /stream/video.mjpeg) are used to embed the video into the STS-Pilot web UI. This app was developed for increased video performance (UV4L) and better resource usage (PyPy3).
Check the GitHub repo for more details.