This repo contains a presentation timer overlay with a progress bar. The timer can be controlled (start/stop, reset) by a small web server. I use this in some of my seminars.
python3 timerbar.py --duration-minutes 10 --server-url <server_URL> --auth-token <token> --ca-cert cert.pem
python3 server.py --auth-token <token> --host 0.0.0.0 --port 5000 --cert cert.pem --key key.pem
https://<server_URL>/?token=<token>
Security is vibe coded. It should just make it harder for seminar participants to interfere.