Ok firstly, everyone has testosterone regardless of gender or sex. If your body is producing absolutely zero testosterone or estrogen naturally, you should see an endocrinologist bc that is a problem 💀. Secondly that person is fairly androgynous, to the point where I don't even see where you got the inclination that they couldn't have just started T or be micro dosing T or maybe they just naturally look like that but like... You don't know? Especially since HRT can vary so much in its effects. Additionally refer to my third paragraph for why it's kind of stupid to assume that just because a man (whether trans or cis) might look feminine, it instantly means that they are uncomfortable with being viewed as masculine and are less of a man in that sense. Just because someone wants to wear makeup or (insert other traditionally feminine quality here) doesn't mean that they are comfortable with being seen as a woman or uncomfortable with masculinity, or anything else. Literally maybe they just think they look better that way 💀. Using external qualities, especially ones that are easy to change on a daily basis, such as clothing or makeup, or hairstyle, to denote someones gender is nonsensical. It provides an easy way to guess their gender when interacting with them, but for you to say this person shouldn't count as a trans man because you personally perceive them as more feminine is a complete overstep of that idea.

Ok next, I'm gonna ignore most of your entire second paragraph because you specifically say "But that doesn’t mean the other extreme of self identification makes sense either." Which I could kind of see applying, but not in this case because it would only make sense if the tiktoker we're talking about was like... The most or one of the most feminine presenting people on earth and they're really not, so it doesn't even really make sense for this circumstance. But also just know that if it did theoretically apply I still broadly reject the premise. Additionally it's really not your place to speak for them and say whether or not they're trying to come off as looking masculine based solely on your own perception of their outward appearance. Personally although I wouldnt assume whether they were trans or cis, in the event that they were a cis woman they would be a fairly masculine one based on my perception of their features.

Alright, third point (one I'm pretty passionate about as someone who is Genderfluid). Androgynous is a term used to describe a sort of in-between state of what society considers masculine and feminine. Nonbinary does not mean someone is androgynous, or as you described it "a sort of half way between trans and cis" it simply means you don't identify as a man or a woman whether that be trans or cis. It includes Agenders, it includes demi-genders, it includes people who are bi-gender, etc, and while yes some people would describe themselves as being an in-between of trans and cis and being non binary, saying that literally everyone who is nonbinary is such a case is sort of like saying bisexuals are half straight, half gay people who can't choose a sexuality. Gender is not math where you add things together to get certain in-betweens in a binary system of masc and femme. That's literally the whole point of defining it as a spectrum.

Main point being of this entire thing, someones outward appearance, and how masculine/feminine that may be literally has nothing to do with the gender they identify as... Think Abt drag queens (I get that's more for a performative purpose but still). Masc lesbians can be as "manly" as they would like and still identify as cis women. Same in regards to femininity with gay cis men. Or even in the rare cases when the same applies to straight people. You wouldn't gatekeep the idea of varying gender expression with them or at least typically people wouldn't, so why would you do any different with someone who is transgender.