Is there a command that allows me to launch Thunderbird's Lightning from command line? I want to add a command to the Thunderbird launcher that allows me to open to a Lightning page.
There is currently no way, at least not a known easy way, to start lightning directly from command line. There is a bug tracking here: https://bugzilla.mozilla.org/show_bug.cgi?id=359807
You can add yourself to the CC list (as what i did) to get updated about this feature request.
Sunbird is the standalone calendar, but it has been discontinued by Mozilla, so I cannot recommend it for you.