No G Suite, but the Linux Plumbers Conference (https://linuxplumbersconf.org/2018/) is making use of it, though with some substantial modifications to make it more mobile friendly. I also wrote (https://lwn.net/Articles/758878/) a review of Indico on LWN for the curious.

Experiments at CERN use it. ATLAS has clocked 260k meetings, whilst CMS had around 130k.

As I mentioned in my reply to OP, > 200 known servers. There's no built-in G-Suite integration, but there's always the possibility that someone will write a plugin for it.

And if anyone is interested in contributing - be it G-Suite related or anything else: Feel free to pass by our IRC channel, #indico on Freenode!