I have 30mm Grand Prix 5000 S TR on 26mm internal hooked rims, they measure as 32.5mm wide and 27.2 high. There's enough side clearance in the fork (around 6.5-7mm), but tire height is the main limitation with only 4mm of free space. The situation is reversed with the frame. Even with the same tires and wheels, there's only about 4.5mm of side clearance and over 8mm of height clearance.

Here https://youtube.com/watch?v=-k5TzYEYwJg you can see that RD battery easily removable, i hope Wheeltop will sell batteries separately as other spare parts. Also video contains some instruction to prevent water ingress, you can turn on auto translation for subtitles, they are decent.

Is that corrosion I see on one terminal of the battery to how it mates with the derailleur pins?

Yes.

I have been reading so much on the forum that it is now so confusing to choose a "good frame"

I was originally going for LC017 but the down tube being as straight as a wall which is a no go, now I think that I will go with the Hygge model S but I can't find any picture with a clear view of the down tube shape.

Has anyone had experience with a bending head tube when you push on it (it is a common issue I've read about LC017)  with this frame ?

PS: If anyone wants to suggest me a frame I would be glad, I'm looking for a light climbing bike but not at the cost of aero like LC017 down tube.

Headtube on my bike is solid. Here some photo of downtube, hope it helps.

3000 km update.
I have no issues with frame stiffness, a flexy handlebar with 30mm Grand Prix 5000 S TR feels very good, especially on a bumps. I've hit some potholes and poorly constructed storm drains (well below the asphalt level) at high speed without any damage to the rims, handlebar, or frame, only get pain in my palms and wrists.
The headset is also holding up well, with no play or marks on the steerer tube. The seatpost, tightened to 5 Nm, hasn't slipped at all.

As for the ZTTO hybrid brakes, well, they work. They're slightly better than my old rim brakes with SwissStop FlashPro Yellow King and Elite ENT wheels. However i can't recommend them. The force that needs to be applied to the brake lever to stop almost the same as on the rim brakes, and pistons doesn't work evenly. One piston barely moves, and there's some flex in the lever arm that pushes the hydraulic cylinder. In my opinion, mechanical calipers like Avid BB5 or BB7 would be a better choice.
The brakes also squeal at low speeds. I suspect this is due to the cheap pads (only $4 for two pairs). I've tried cleaning the rotors and pads, but the squealing persists. As a result, I've ordered Ashima ceramic pads, hoping they'll solve the problem.

I swapped the crankset to a Shimano 105 because the ZTTO BB for a 30mm spindle started clicking after 1,000 km. Since I already had a Shimano BB and cranks, I decided to save money by not buying a new BB for the 30mm spindle. To shave off some weight, I replaced the 105 chainrings and bolts with Ultegra ones. This brought the total crankset weight down from 750g to 698g. Interestingly, the 105 and Ultegra cranks without chainrings weigh the same.

Finally, I experienced some clicking noises from the rear axle. This happened when I switched the bike back and forth between a trainer and the rear wheel without properly cleaning the dropouts. Thankfully, a thorough cleaning solved the issue. I'm unsure if this is normal or not, as I never encountered it with quick-release skewers.

Today i saw this Twitter bikes catalogue, interesting that full carbon bike with wheeltop eds tx costs 950 USD, I wonder how much a wheeltop costs for a factory.
Rival upgrade kit I can find for around 1000 USD, 1525 - 905 = 620 USD difference between rival and eds versions, so 1000 - 620 = 380 USD for eds? Maybe lower, because rival also has a wholesale price.

I had to apply a good amount of grip paste to get the expander plug to prevent slipping. I torqued plug to 6nm and it's fine.

It looks like Hygge is just one more seller that is friendly and supportive when they want to sell you something, but the opposite when you need them to fix a problem.

Congratulation, you discovered a typical seller/brand that sells very cheap products.

They (and many others) sell a frameset, sometimes with a handlebar, for 450-550USD, it's 3-5 times cheaper than cheapest options from a big brands. And for me it's strange to expect, that they want to spend 50-100USD to replace handlebar with bad paintjob. With these cheap chinese frames you just play roulette, with high risk, high reward.

And about handlebar, I suggest you or forget about it, or start to write them on social networks, aliexpress chat, mail etc. This might lasts weeks. If you still can - open aliexpress dispute.