Is it possible to receive SIP client register events with ARI?

I’m using ari-py to listen to channel events successfully but I was wondering if I can also receive an event when a sip client registers with asterisk? Is it something to do with devices?

There is no ability to receive an event when a SIP client registers, the only thing that comes close is subscribing to device state for the device and you will then receive an event when the device becomes reachable and unreachable.