you can invite people from outside your org to meetings, but yes, it's not a purely public service. Duo and Allo are still out there though.
Ah, yes, ye olde "Google Apps for Domains" (boy, there's a catchy product name ...).
I've got three of them still running: two I rarely use, but the other is the family account and it's got a lot of history in the mailbox.
I'm gonna be effed if/when they pull the plug on us greybeards still rolling on that old free tier.
/Acey
p.s. The new Gmail theme sucks rocks. Anyone have a 411 how to make it look as near to the old style as possible. (tbh, I haven't hunted for an answer, but tacked this on in case anyone reading knows a good blog for that.)
One being a family account also is even more problematic, they expect Gmail quality web interface and I can't really give that to them.