... This is better worded as follows:
Windows XP is well alive in 2019 China
since
are ALL browsers offered by Chinese vendors (and mainly target mainland China users...; I won't even touch the privacy concerns associated with Chinese browsers in general ).
The fact that XP still holds a strong market share among Chinese netizens is the very reason that gives incentive to these Chinese vendors to invest, no doubt, considerable resources to (probably manually) undoing all the many thousand lines of code Google have pushed after Chromium 49, so as to restore XP and, probably as a not intended by-product, Vista compatibility in their Chromium 69 & 70 forks.
Being myself in the Mozilla camp, I would've liked for them to have similarly produced an XP/Vista compatible Quantum fork, but I suspect they were not interested in such an enterprise (technical limitations aside): Quantum currently enjoys only a small fraction of Google Chrome's usage share; and Google Chrome is already on its own a hugely more efficient spyware than Quantum, so why bother to begin with?
Of the rest two browsers in your first list, Nano Browser (still in alpha testing phase) is an Indian product (another territory where XP is still abundant), while Lunascape is a Japanese product (which makes it the odd one out, I suppose; BTW, have you checked that the Gecko and Webkit engines inside Lunascape are indeed XP compatible? If not, Lunascape would be only able to use IE8's Trident engine under XP and that alone, as I'm sure you already know, won't get you very far in 2019's web ).
PS: This is not an XP dissing post, I still love XP myself, having spent 6 years on it before sticking with Vista; but it is a reality check all the same...