Hangouts is also solid proof that no-one at Google uses a non-Chrome browser on Android: trying to open a meeting hangout invite with anything other than Chrome as the default browser … opens a link to Google Play, not the Hangouts app.

I think this is because they use a different URL in meeting invites than the one registered for the Hangouts app.

It's been a bug for ages, and AFAICT they just don't care.