Given a STA of 73, that results in a horizontal setback of 15.68. So not a big difference, assuming I got the trig right.
Eyeballing the drawing, we're losing another 10mm relative to the center of the seat tube though.

I noticed that the Nextie G2 has the exact same geometry: https://bikeinsights.com/compare?geometries=648f566fec82fc001a96df32,65c2a0c6a244e9001aeae09c,
except for 10mm longer chainstays.

Yeah, the Nextie G2 is the same as the BXT 135 in which I was also interested - before I read about experiences with them. The frame has also 2mm wider tire clearance which goes for me into the wrong direction as I want max 40mm plus optional 30mm tires. But yes, given the quality of the G2 is good it should be a great alternative.

Regarding your maths. That's true, but I still don't know what the blue line is referring to. It seems so randomly placed. But since it is far from the center of the seat post the real setback could be indeed ~25mm.  No one caring about geo would buy this frame. Too bad since I really would have liked it. 

Hmm. My experience is from BB30 but I am not alone. I have CAAD 10 and SSE2 both from 2014-15 timeframe. The CAAD came with squeaking bb when I bought it last year. Punched out the bearings and installed new (Wheels Manufacturing ABEC-5) and after a couple of months they started squeaking. I haven't changed it to thread together yet so I clean and lubricate every time squeaking returns. The SSE has Token thread together BB on it and it works fine. Its still technically press fit but I like the idea of two cups attaching to themselves than just latching onto frame.

The problem with BB30 and BB30a bb shells is there is no traditional bottom bracket as such - its just bearings pressed in and a c-ring prevents them from going all the way in. Those bearings, c-rings, and two cups/reducers to space out crankarms form a bottom bracket. If Loctite is used it will be around the bearings directly and if it bonds the bearings to frame, its frame dump the next time bearings need changing. Loctite is a big no there. Same thing with Trek's BB90.

When you say I use good quality BB with replaceable bearings, are you talking about BB386/PF30?

You're right. I was thinking about pressfit bbs with shells. I would not buy a frame with BB30. SRAM went away from this standard pretty quickly it seems.

I got an answer concerning weight:

Thank you for following and contacting us.
SP-G068 has currently completed sample manufacturing. The sample size is size M, the frame weight is 1120g, and the fork weight is 445g, excluding metal accessories. The downtube of the G068 is very large and thick, so it’s difficult to make it very light.
We are considering using full T1000 carbon to make this frame. It is expected that the mass production version will be size L and weigh 1100g.

best regards

David

He didn't answer my question regarding price. But I would imagine it is similar to the other gravel frames. That would be quite ok :-).

Have heard BB shell bore not perfectly round but haven't heard threaded insert coming loose. For me manufacturers going back to threaded BBs (BSA, T47) is a very welcome news.

Staying with anecdotal observations. I never had issues with pressfit and if so I would have either bought a bb with a threaded inner shell - or simply glued in the shells with Loctite 683*.
From an engineering perspective the advantages of pressfit overweight the downsides. The biggest downside of pressfit is it's reputation because people are unaware of the proper installation process. Maybe I have to correct myself by saying the biggest downside of pf is therefore the higher chance of improper installation as opposed to threaded bbs.
This is also covered by "peak torque". I just couldn't find the video in which he said that. But while searching for the vid I came across another video which explains this topic: https://youtu.be/33IWHSGl1nU?si=an7GdPbuU_WQ3gx-

Btw. I asked them a few questions:
is it possible to provide an own logo for the frame?
---Sorry, no
do you also offer the Graro fork without bolts?
---Sorry, no
how big is the setback/offset of the seatpost?
---15mm
do you offer a seatpost with less seatback?
---Sorry, no
is it possible to order the frame in pearl white and fork in chameleon?
---Yes.

* "wtf?! You would end up having worn bearings and therefore a frame to be dumped." Actually no. I just use a good quality bb with replaceable bearings.

The Carbonda one has a 67º HA, this is not what we had in 2018 

Really?! I mean that would be awesome. But the specs tell a different story. https://www.flybike-asia.com/product/260.html

Hi guys, I'm desperately looking for a hardtail frame with modern geometry similar to the Spot Rocker. Something like this:

fork: 120mm
reach: 460-485mm
stack: < 630mm
head tube angle: 66-67°

Another option would be to use a 100m frame with a geo like this and turn it into a 120mm rig:
reach: > 470mm
stack: < 610mm
head tube angle: < 68°
effective seat tube angle:  >75°
bb offset: at least 62mm

The closest ones that I've seen are (but not close enough):
- Spcycle M016
- SP-M05 (https://www.aliexpress.com/item/1005004067264835.html)
- Carbonda FM-1306

Is there even a modern carbon hardtail out there?

Great info! And just my thought about the frame durability. Getting a 2nd hand Fox 130mm travel next week that I will try on the bike.

The seat tube angle is already with a 100mm Fork on the edge. Sure you want to push it even further?