Congrats, that is awesome!

This looks like a spiritual successor to the Niner MCR 9 with upgraded bottom bracket, udh, and storage.
I have had a 165x38 X-Fusion O2 Pro on an XC frame and it was really good but you'll probably need to use the lockout a lot.  Hopefully they put some thought into what type of tune they suggest, the Niner X-Fusion shock has a short stroke and a custom tune.
Rockshox Rudy XPLR is pretty good but I would consider the Cane Creek Invert because it is cleaner looking and probably a little lighter.  Couldn't tell by the specs or description if it is internal headset routing or if you care about the front brake cable, not much if anything on the market yet for internal routing until the DT Swiss gravel fork is available.
With the AXS mullet and the capability of a full suspension gravel bike, I still like a dropper.  Reverb AXS XPLR because why not, the disappointing thing is that the longest drop available today is 75mm.  Shame that they didn't go 30.9mm for more Reverb options.  Ton of 27.2mm cabled options but every drop bar dropper lever sucks.
Similar taste in wheels as well, I have some aliexpress brand I can't remember 6-spoke carbon marble with Pirelli tires.  I love it, but I do get some 80s BMX mags comments every now and then.
I'm sure you've seen similar setups in general internet searches but let me know if you want pics for comparison.

Ordered a LCG073-D about a month ago with a single color paint and it shipped a few days ago.

...what was the cost?

With paint, shipping, and fees it ended up being a little over $900USD.

That is interesting, can you post the listing you used?  I found one that is similar with a picture of the branded frame but it had an older generation geo chart (67 degree HTA, 74 degree STA) and the rest of the pictures were the Himalo frame images.

If the Rekon is the tire you're after, you're in good shape since they run narrow.  I have a 29x2.4WT and it measures a little over 2.2 on 30id rims. 
The 27.5x2.35 Bontrager XR3 on 25id rims also measures a little over 2.2 so there was plenty of room. 
As another test I put in a 29x2.8 Teravail Coronado that measures just about 2.7 at the edge of the side knobs - it fits but only just.  I think just having weight on it would make it rub.
I also don't believe the reduced circumference of a 27.5 will get you any more space.  Anyway, best to google some measured widths of a tire you're considering just in case.
Some visuals:

The original build thread: http://chinertown.com/index.php/topic,3445.0.html
Frame is painted Pantone 11C (Cool Gray)
1st generation triangle with JJJ bolts included, new triangle installed
Shipped anywhere in the US for $550, with a Rockshox Super Deluxe Ultimate 210x55 with MegNeg $850






Shock has been serviced relatively recently, hasn't been used in a while.

Had the same thing happen to a ZTTO 9-50t 12-speed XD cassette.  Mine didn't even last one ride around the neighborhood so I think you did pretty well at 3000 km.

HG is a safer bet because it is hard to mess that up.  After the ZTTO experience I use an established player for XD or Micro Spline. 

Wow, I'm happy I found this thread! I just got my frame and I'm building it up. I found that the rear of the frame is skinnier than it should be. I try to put my hub in (normal boost hub), and I have to pry the frame apart about a cm to get the hub in. Has anyone else had this issue? I don't think it is the end of the world, but I am a little worried that it will make the derailleur hanger a tad crooked.

I have two of them and neither rear triangle has that issue.  Being aluminum it can be "stretched" and the the hanger can be aligned but that does suck that it came that way out of the box.     

got a link? I wouldn't find one. I prefer Rockshox Shocks over the Fox

I'm having a hard time finding the nylon flat washer kit I have, I couldn't find it in my order history from Amazon so who knows... I'm not finding an M8 x 1mm thick nylon washer on a Google search either.  It is just to pick up slack so it doesn't have to be anything great, a stainless or black oxide would also work.   

Alternatively, you can get a couple sets of these:
https://www.enduroforkseals.com/products/rear-suspension/shock-eyelet-bearing-kits/6mm-8mm-thru-bolts/SS8x17x0.5.html

The second frame has a Fox DPS with one of their needle bearings which is just as good as the roller bearing on the Super Deluxe.  It'll work on anything with a standard eyelet.
https://www.enduroforkseals.com/products/rear-suspension/shock-eyelet-bearing-kits/6mm-8mm-thru-bolts/NEEDLE-BEARING-30.html

I bought that Santa Cruz specific Super Deluxe Ultimate with the roller bearing thinking that Haideli put the right shock specs in for the AM831.  Of course, they had the information backward so I couldn't use it.  I actually sold it 4 times - 2x on eBay, and 2x on Pinkbike - and because people didn't read the big bolded warnings it was sent back every time   I'm happy that it works in this frame since replacing the damper is a huge pain and I obviously can't get rid of it...