In theory, they could work.  The problem area could be with the spindle's  splines that mate with the crank arms. Are the machined splines, aka. (Wave taper interface) machined exactly to the SRAM standard?  It is possible that visually they look similar, but due to SRAM patents, they have made slight changes, and might not properly fit in a true DUB or GRX based crank am.   Crank arms could come lose, or get stuck on.
Specifically ask the seller if their spindle is 100% interchangeable with SRAM DUB or GRX

Also confirm if the axle lengths of 121, 125, and 129 are measured end-to-end, or outside-to-outside of the bearing surfaces.

I have been looking for 30mm diameter spindles that fit Race Face Cinch cranks since their prices doubled this year for OEM Race Face Spindles.

My situation is easier, as I don't plan to reuse an old crank, but buy a new one with a longer spindle... If crank and spindle are from same supplier, chances are high that they match. Just wanted to know if anyone have tried already...

Anyone tried using Hudud or Ullicyc carbon cranks with wider spindle?
I plan to build a 2x gravel bike and need to push the chainrings 2.5-3mm out to clear the chainstay and tire.
There are no "GRX" or "DUB wide" Chinese carbon cranks, but noticed that Hudud and Ullicyc are selling different length spindles on AliExpress which should do the trick. Anyone tried this?
https://pl.aliexpress.com/item/1005012728048415.html
(I have a suspicion that the TI spindle can actually be used on all the similar carbon cranks, as they probably sourch from the same vendor)

Also interested
Want to build a 2x gravel bike with a powermeter and need dub wide to clear the small chainring.
Currently using a ThinkRider PP5 with single chainring on another bike and that would not work in a 2x configuration

I'm doing almost exactly the same build currently 

Frameset: LightCarbon LCG071S-PRO (52cm, UD Black Matte, T47 BB, incl. 100mm stem, seatpost, fork, and thru-axles) - mine is chaemeleon color
Wheelset: LightCarbon 40mm Carbon (26mm inner width, Ceramic bearings, 36T Ratchet, HG Freehub, Centerlock) - Went for MicroSpline hub, see below
Groupset: Wheeltop GeX (12-speed Wireless) - Same (but I use Ultegra calipers)
Crankset: Senicx GR3 - Went for Thinkrider PP5 carbon with powermeter
Bottom Bracket: ZTTO T47-24i - same
Cassette: Sunshine 12-Speed (11-50T, HG Spline) - After my experience with a wobbly ZTTO 11-52t i went back to Shimano XT 10-51 MS spline. The build quality and the alluminium spider is SO much more sturdy
Chain: Shimano XT CN-M8100 (12-speed, 138-Link, w/ Quick Link) - same
Rotors: 2x Shimano RT-CL800 Ice-Tech (160mm, Internal Serration) - went for IIIPRO A2 ultralight 160mm half price
Handlebar: PRO Discover 20 Gravel (44cm, 31.8mm clamp) - got the integrated from Lightcarbon
Pedals: Shimano PD-EH500 Explorer (Hybrid: SPD/Flat) - Shimano PD-ES600 - no hybrid
Tires: 2x Tufo Gravel Thundero HD (700x44c, Skinwall, Tubeless-ready) - Goodyear Eagle F1 tubeless 700x32C for now, not going offroad yet

Biggest difference is to stick to Shimano , based on previous experience of a chinese MTB cassette...

I'm looking for something similar to build a travel bike where it's easy to remove the handlebar for packing
Best (only) thing I've come up with so far:
https://www.aliexpress.com/item/1005009161962780.html
This would allow routing cables through the center hole of the handlebars, into the open bottom stem and down the headset and leave plenty of cable for removing the handlebar to place at the side of the frame for packing.
Anyone has a better/neater solution I'd love to know... (other solutions route through the hollow stem, so leaves no slack in the cables when the removing the handlebar)

I seem to be in the same boat as you, I have these 2 now for testing - will report back when I did some km.

https://de.aliexpress.com/item/1005008741976302.html
https://de.aliexpress.com/item/1005007468205835.html

Let us know how it goes...
Currently using a Specialized Power Comp clone similar to MIXED 6D in 155mm width, but looking for a longer saddle in 150mm width.
Did give Ryet Aircode 3D a go, but it was stiff like a plank, maybe aggregated by me being a heavier rider...

The build is done and I took it out for its first shakedown ride. Somehow I nailed the fit just by vaguely replicating the dimensions I measured from my G068, so I didn't even have to stop and adjust anything, and 7 Nm on the seatpost clamp is plenty. I don't really have much to say about the build process. Everything was completely fine (except dealing with the hassle of a dropper with internal routing, seriously, don't do it), all the surfaces were faced and all the threads were clean, hoses popped out where they should, it was great.

I do have a few notes about the frame, though:

• The only flaw I could find on the frame, or rather in the frame, is that the ends of the channels that divert cables/hoses around the downtube storage hatch opening have some excess resin from when they were bonded in, and this resin has cured to form mildly sharp bumps. They aren't big, probably only ~1 mm high (I can only feel them, there's no angle to view them), but it's necessary to use foam housing all the way up to the channel entrance to avoid potential hose damage. The channels aren't big enough to accommodate foam housing though (at least not easily) so some careful measuring is necessary to get the foam housing length right.
• Part of my decision to buy this frame was that it listed 160/180 mm rotors - but this is only true for the frame! The fork is 140/160 mm!! I'm not too happy about that, but I can live with it for now. I bought one of the cheap 180 mm adapters off Aliexpress to see how that works, maybe I'll keep it, maybe I'll spring for the Peak Torque BBC ($75 though...). I also emailed them about this and they've corrected the frame specs on the AF website to be more clear, so kudos for a quick response there.
• The internal frame storage is somewhat limited - the included bag is good and is a snug fit, but no object longer than about ~3 inches can be put in the bag lengthwise, because the bag needs to be able to articulate to be crammed up into the downtube. It can't go down towards the bottom bracket because of the below-downtube water bottle cage rivnuts. The bag wasn't large enough to fully contain my (slightly overkill) tool kit, so I split the lesser-used tools into a separate ziploc that I wrapped in two shop towels and wedged beneath the hatch. This worked well and there were no noises even on some very washboarded dirt, and the bags haven't moved a millimeter. Unfortunately I can't put my jacket in the downtube, it won't fit unless I take it out of its protective sack and I don't want it to rip.
• There's no clean way to plug the hole the the bottom bracket for front derailleur cable routing. Ideally a little rubber plug would be included to patch this up, as I'm sure many, if not most, of the buyers of this frame will be running a 1x setup. I used some Sugru to seal the hole but a first-party method would be preferred.

Overall, it seems like I got what I wanted: nearly the exact same geometry and handling of my G068 but with superior manufacturing quality and a few additional features. And the fork doesn't creak!!! I only wish the seattube was a bit longer so I could've kept my OneUp dropper, PNW is not the same quality. Oh well, can't have everything...

Thanks for the detailled description and all the pictures. Frame in the chaemeleon color looks absolutely stunning!
It's between this and the LightCarbon LCG071S-PRO for me. Very similar geometry, although the AF01 is a more compact frame
What did you use to replace all the mounting point screws? Also Sugru?