UPDATE: as of April 17, 2017, Android Marshmallow is now required for web Bluetooth on Android: http://crbug.com/694332
First of all, thanks for the question. You are not the only one for sure ...
As mentioned in https://github.com/WebBluetoothCG/web-bluetooth/blob/gh-pages/implementation-status.md#notes ,
The Chromium tree tip builds on Android Lollipop or later for the convenience of developers - but Chrome versions will support Marshmallow or later.
So, how to play with web bluetooth in Chrome for Android Lollipop:
- Open the Android Settings app
- Make sure Developer Options is unlocked and accessible - help
- Select "Developer" and enable "USB Debugging"
- Connect your Android device to your computer.
- Accept a USB Debugging session on your Android device.
- Download the latest version of Chromium for Android at https://download-chromium.appspot.com/?platform=Android on your computer.
- Extract the downloaded
chrome-android.zip file to the ~/Downloads folder, for example - Install ADB on your computer if it does not already exist
- Install Chromium by typing
adb install -r ~/Downloads/chrome-android/apks/ChromePublic.apk in your shell - Open the new Chromium app on your Android device.
- Accept the invitation for the location of chrome by going to https://www.google.com , for example, a placement permission is required to access Bluetooth in Chrome for Android Lollipop.
Finally, enable the experiment flag in chrome://flags/#enable-web-bluetooth and / or request an Origin Trial token so that your website can use the Bluetooth web interface API without any flag.- Play with some web bluetooth samples at https://googlechrome.imtqy.com/samples/web-bluetooth/
Notes:
A warning! Chromium build for Android will not automatically update like Google Chrome. If you want the new version of Chromium to test new features, you will have to re-download it and reinstall it on your Android device.