This is an unofficial Web Bluetooth-based intervalometer for Canon cameras by @RReverser.

Check out the code and description on GitHub.

If you're comfortable, feel free to try it out with your own Bluetooth-capable Canon camera (entirely at your own risk!):

1. Start the Bluetooth remote pair process on your camera.
2. Set your camera to the "Self-timer: 10 sec/remote control" drive mode.
3. Set your camera to the "Bulb" exposure mode.
4. Press Connect and choose your camera among the shown devices.

Occasionally you might get pairing issues or reconnection issues, e.g. after camera got asleep.

When that happens, I found it helpful to "Delete connection information" on the camera, restart it and go through the pairing process again.