Shorter chainstays and a slightly steeper seat tube would get me interested. This would probably reduce the top tube length by a bit as well.
Well...I take it back, I'm officially interested. I had a steel gravel frame built for me with custom geo earlier this year and I've since finished a couple of races on it. I've since been toying with the idea of building a new steel frame with some geo and tire clearance updates, but realized the GR021/NOAH in size 54 is basically the same as what I had in my head, for a lower price point and the bonus of downtube storage.
I ordered a raw frame from Longteng, which is slightly more expensive than Tan Tan but with faster shipping options. They said the frame was "in stock ready to ship". Turns out it's not in stock and production will take at least 10 days, but it's no big deal, I need time to think up a paint job anyway.
Will be transferring the TRP/Eagle AXS groupset from my other bike for now but looking at GRX mechanical, Ekar, or a Force 1 groupset I have sitting in a box for the long term. With the Force group, I'd have to get the Ratio 12 speed mod and a Garbaruk cage.
I would build it with the LTwoo EGR if it allowed for a cassette larger than 46T.