I just checked with Firefox Focus on Android, and the 'launch' button is missing. Even if I go to the `/messages` URL I am redirected back to the account splash screen. That's my default browser, especially as I only wanted to log in for a minute to check on something on my personal device.

It does work with Firefox on Android (not Firefox Focus), if you check 'desktop mode'. Weird that you should have to fake the user-agent string to access it.