Looks very interesting !
My “wish” is a little bit different :

Each of my groups is a call from another city agency.
So I would like to configure the line buttons on my SP962 phone to see the status of my groups/queues = call from which city.
It should be like that (work like that with a SPA9000):
When there is an incoming call to a groups/queues, the line button on my SPA962 (with SLA to the group) should show me there is an incoming call (i.e from L.A.) to this group.
On the line buttons on SPA932 sidecar I can see which phones ringing or took the call.

How can I make this ?
In my case I would like to see the status of the group.
I do not know how to configure the SLA for this on my phones.
The “normal” SLA works for extensions on the phones connected to Asterisk.