You've pretty much got redundant everything. 3 separate inflation systems - the I3 on the BC, the SS1 as an alt/octo on reg - which you'll use if you donate the yellow B2 and the drysuit inflation - which I suggest you use last - maybe take a class on that - it's pretty easy to invert in a drysuit if you get too much air in the legs. Also if the drysuit leaks - so does your buoyancy.
As mentioned above, you've got dual air redundancy also - IDK what Nolatom meant - you've got two pressure "gauges" - the transmitter is sending air pressure to the D6 Novo (it's doing calculations with it also) and the Cobalt on the hose also reads tank pressure.
Lastly you don't need a "2nd reg on that yellow hose" - that's probably your drysuit inflator hose. You've got two 2nd stages with the B2 Octo and the SS1 - Atomic designs both to breathe the same. Why didn't whoever sold you the stuff just sell you a standard B2 2nd stage instead? Are they trying to indicate that the B2 is the reg you'll donate to someone else?
I personally would not want to indicate that the reg I'm normally breathing on is one to be grabbed by another diver in an emergency since they're likely pretty stressed and grabbing for anything they can breathe on - potentially ripping it out of your mouth.
The Aqualung's Dimension has weight integration - the two gray handles shown are the Surelock system. So you don't need a belt.
I don't see that you're missing anything - maybe a good light? How much light depends on the water clarity where you dive. 500 lumens seems like a good compromise for lighting, signaling yet not scaring the fish away. eLED IMO is the only way to go now.
If you buy shears, make sure the pivot is stainless - my cheap pair rusted after the first ocean dive. The blades were fine but the pivot rusted closed.
In about a year invest in the correct computer/transmitter batteries and throw them in your bag. You'll only need it when you're somewhere they don't sell that particular one.
I'm a fan of Cobalt screen ever since I first saw one. If they ever do release a wrist version, I'll own one.
