1. Can see the similarities. That's odd considering how Zhongyuan Han are genetically much more northern than Hmong, who seem genetically to be in the Southern Chinese cluster.

2. Northernmost and westernmost she can pass are Shaanxi, Gansu, Qinghai? Can she pass among Hui or they look different? Eastern Tibetans look different from other Tibetan ethnic groups?

4) Right. But isn't her eyelids smaller than the other Akha lady?

5) Would you say Tibeto-Burman and Hmong-Mien ethnic minorities in SE Asia are more northern-shifted phenotypically than Northern Vietnamese Kinh who have substantial Sinitic-related affinity?

Disclaimer: I haven't been anywhere in China for over 10 years by the time you will have read this, and within China I've never been anywhere south of the Anhui-Jiangxi-Hubei tripoint (which I'm pretty sure is south of Shanghai). My phenotype knowledge of China and "bulk Han" is heavily based on Asian Boss and other YouTube videos and the people I see in the US (or on dating apps). My phenotype knowledge of Mainland SE Asia is mostly based on Overseas Vietnamese (very common where I grew up), Overseas Cambodians, and the fewer ethnic Lao + Thai nationals + members of other "hill tribe" groups I've met in person.

1. {Hmong Tiktoker} Facial structure is too neotenous, eyes are too big to comfortably pass as Han within China. As throway said this could be a makeup + filters issue

2. {Ahka Tiktoker} She passes further north IMO because she has a Tibeto-Burman look that's shared with "bulk Han" which most Mainland SE Asians generally don't have unless they're part of a Tibeto-Burman speaking group and not just part-ethnic Chinese.

3. {Facebook profile} Can only see two photos of her, but her facial structure is very distinctly "South Mongoloid". Facial fat seems rather distinctly "Central Mainland SEA (Thailand/Laos/Cambodia)- I don't really see this look among Vietnamese, for example.

Can't see your #4 unless I'm open the link while logged in, but 5 and 6 give me Chinese Indonesian-like vibes. Don't think either could comfortably pass in China, although 6 has more of a "Taiwanese" (and thus Chinese-passing) look than 5 with her eye shape and nose. When I say Chinese Malaysians/Indonesians look different from China/Taiwan/HK Chinese, I mean that I see people who resemble your 5 and 6 whose phenos don't really exist in Greater China.

1) How much Hmong-like input do Zhongyuan Han have? Is the She of Fujian also Hmong/Miao? But why are the Hmong/Miao genetically pretty southern-shifted if they lived very close to Zhongyuan? The Miao G25 results seem to be as southern as the Chongqing, Fujian, Sichuan Han while the Hmong from Thailand G25 seem to be very significantly Dai admixed and is more southern than Fujian but slightly north of Han_Guangdong samples. 

Would Ancient Sinitics such as Xia, Shang, Zhou seem to be closest genetically to modern day Zhongyuan Han ?

2)  I C. Does Naxi, Yi look more like Qiang/northern Han and Eastern Tibetans while Tibeto-Burman Northeast Indians, Nepalis such as Sherpa, Tamang, Gurung, Sikkimese, Bhutanese look more like the Paniya-like Tibetans?

4) True that. 

5) Make sense. Correct me if I'm wrong but Northern Han seem genetically much closer to Koreans, Japanese than to Tibetans though. Is it me or South-Central Chinese look more like Hmong-Mien while Northern Han gives more Korean, Mongolian look?

You've probably never seen a real Austronesian person then. They look very distinct from any group of East Asians except those in the extreme south such as Guangxi or southern Yunnan.

Here's a video of a collaboration song between Taiwanese aboriginal singer Abao (the woman in the video) and Taiwanese Hokkien singer DJ Didilong (the guy in the video). Although it's probably not very suitable to compare a woman to a man, still I find the contrast in their phenotype rather striking. The Hokkien singer can easily pass in Northern East Asia such as Shandong or Korea, whereas the aboriginal singer Abao cannot pass anywhere further north than Lingnan and Yungui.

1) While it's true that the Sinitic population largely exists on a cline or a continuum stretching from NE Asia to SE Asia, there's a still a considerable genetic distance separating Zhongyuan Han from actual SE Asians. The closest Sinitic population to SE Asians are the ones from Guangxi. It's perhaps true that Northern Chinese probably look a bit more SE Asian compared to isolated Himalayan Tibeto-Burman tribes who have few to no SE Asian admixtures whatsoever, but compared to Far South Chinese and actual SE Asians, Northern Chinese still appear rather northern-looking.

5) Koreans and Inner Mongolians definitely have a large overlap with Northern Chinese in terms of appearance. And in terms of genetics they are also the closest non-Sinitic population to Northern Chinese, closer in fact than the genetic distance between some South Chinese groups and Northern Chinese.

Taiwanese Aborigines are not all the same. Ones in far south Taiwan like Abao will look different to Atayal like groups living in northern Taiwan mountains. The latter are more Japanese passing.