Just doing a local build of your repo (outside of Cloudron) and modifying your start.sh so that output is done to the container, it reports as running on port 8000 (on localhost, but also globally). /healtcheck does not seem to exist (gives a 404), but / gives a 200 for me. On the browser however it just loads endlessly.
Looking at the devtools on Chrome it tries to load a service worker (worker.js) which only gives a 404, but would anyways need https to function properly.