Looking for blips online, i think i read that you can change chainrings by clicking both blips at the same time.
Seatpost isn't on my radar but i think i read that it doesnt work with blips.

That was the status a few months ago, yes. I’m wondering if there have been any updates since then because it’s unclear to me why a double ring setup would work while the seatpost doesn’t.

Is the 505SL still available? I can not find it on their page?
How much did you pay for it?

Contact them by email, it is definitely available and the new version is a great frame to build and ride.

You need only the AXS RD, Wireless Blips, and a 12-speed cassette with a matching chain. The latest AXS firmware no longer requires levers or a blip box... Also, the force and red chains last a long time and are worth the cost.

Do you know if the recent firmware allows the wireless blips alone to be used in a 2x setup ?
Or paired to an AXS seatpost ?

How funny, these are the two I was also split on! The acros one seems nice for the multiple ports, as I will run mechanical shifting at this time.

From your experience building up these all internal open mold frames, how would you recommend I go for running my two brake hoses AND a shifter housing line? I live in the American Southwest, it is extremely dry so rain/moisture is NOT a concern.

Each time I'm asked for one, I try to convince the rider to consider electronic shifting 
A definite no is cable disc brakes. Hydro brakes are easier to work with and require a fork with an internal hole.

Shifting needs a bit more care, there will be some additional turns in your hose, which add friction. Avoid sharp curves as much as you can.

This look great. Did everything work well with the T-Type?
I am looking for a UDH Carbon Gravel frame to do basically this exact mullet build. Any thoughts? Is the geometry comfortable?

All riders are extremely happy of their T-Type mullet. More than usual when I build a bike 
I'm jealous now...

I've built the first with a Force crankset, max chainline of 47.5mm
And because of a short chainstay, when in the small sprockets the chain was rubbing slightly to the sprocket just above. SRAM's support folks knew the issue but found it acceptable
An additional shim of 1.5mm drive side did the trick, the preload ring, non drive side, being at the minimum.

And now I build them with a XX1 or Quarq non boost crankset( chainline 49mm ). I didn't check but it could be lighter than the force.

About the comfort, I ride for years now the first gen of the CFR505 and I find it very comfy(27.2mm seatpost helps and I inflate my 40mm tires not more than 2.5-3bars)
The geometry of the new is the same as mine, so the comfort is the same.
It is listed in https://geometrygeeks.bike/bike-directory/search/?q=CFR505 if you want to compare it with your bike(s).

I searched for wide rims and found more Q's than definitive answers. But I did find some good options at Light Bicycle like these: https://www.lightbicycle.com/carbon-road-gravel-cx-disc-bike/rims/700C--24-25mm.

Now I get in the internal debate that buying rims, hubs, spokes, and nipples separately at retail prices is the same or sometimes more than buying a complete wheel. I guess the long term value is buying good hubs and then using them with multiple rims over the years, changing out the bearings as needed.

Unless the rider has specific preferences, I guide them all towards the Lightbicycle WR40 rims for gravel/road sets. I used to buy just the rims, but I found that, not counting my hours, the price was almost the same as buying a built wheelset. So now, I buy the complete wheelsets. However, building wheels is still a very satisfying skill.

Both the hubs and rims are incredibly durable. I still ride my first Lightbicycle 29er wheelset I got 10 years ago, and the ones I got from Peter are even older.

Here's a new build with a mulet with the new SRAM Red shfiters/brakes - GX Transmission derailleur - X0 Transmission cassette and chain
And the Lexon gravel bar https://www.aliexpress.com/item/1005004788375665.html which is very nice and stiff

To have a better chainline (49mm instead of the road limited to 47.5mm) I did put a non boost MTB crankset.
So there was no more rubbing of the chain.

The setup app is limited to 38T, so with this 44T I did add 6 links(inner+outer) to the 118 advised.
But had to remove one after testing.

From two other builds, for better shifting, the setup key had to be set on B even if the app was saying A.
But not on this one. So the setup app is not really accurate for mullet builds.

Edit: I forgot the wheels, these are the WR40 from lightbicycle with their carbon aero spokes + ceramic hub v2.0