Correct - for the submissions to qualify the projects need to use Channels.
Of course, you are free to use any other APIs or services as well - and that includes Pusher products :)
And regarding the limits in the free/sandbox tier:
the limit is 100 concurrent connections. You can have more users, but not connected at the same time. You can find more info here: support.pusher.com/hc/en-us/articl...
Correct - for the submissions to qualify the projects need to use Channels.
Of course, you are free to use any other APIs or services as well - and that includes Pusher products :)
And regarding the limits in the free/sandbox tier:
the limit is 100 concurrent connections. You can have more users, but not connected at the same time. You can find more info here: support.pusher.com/hc/en-us/articl...
message counts are as Peter Mbanugo described, you can read more about it here: support.pusher.com/hc/en-us/articl...
The rest is correct