Similarily, I like the POAT photochromic glasses (pretty sure it's a POC clone).  The ones with the multicolour sides are built better than the solid colour sides (they use a different plastic for the solid black or white glasses arms and it feels much cheaper).  One bad thing is the lens pop out once in a while, but you can just pop them back in no problem.

I have 4 pairs that I cycle throughout the year, and no issues with them.  They've survived falling off my helmet quite a few times too, everytime the lens just pops out and once you pop it back in it is good ads new.

I've been meaning to try the SCVCN but I bought too many of the POAT ones...

I have the Rockbros ones that are usually $25 on Amazon.  They have been great for the last couple of years.  Photochromatic adjustments can be a little slow when you move into shade, but I'm not sure how much better expensive versions would be. 

What do you mean by "full Chinese components"?   

- Some of the drivetrains are getting decent, but Shimano prices are so low right now that you might want to look at Deore.   
- For the fork, nobody seems to have done any real testing on some of the new Chinese forks that are showing up, but the last generation were't good (see Berm Peak feedback on Bolany).   Rear suspension is similar - unknown and mostly heavier.
- For wheels, what is your budget?  There are some well reviewed carbon/novotec wheels around, but Chinese aluminum are mostly pretty cheap and poor. 
- Brakes - There is a lot of experience with Zoom brakes, and the four piston ones will stop you bike very well.  However, lots of reports of them leaking and having other problems after a pretty short period.  Good Shimano 2 piston brakes are really, really cheap.  4 piston Shimano are not so cheap, but they are really nice.

In truth, these thoughts are all based on not nearly enough input.  Plenty of people on this forum were willing to try out untested carbon frames and have made it much easier for the rest of us to jump in.  We need some of the same thing with suspension, cranksets, handlebars, etc, so it would be great if you went that direction and reported back on what you found to work/not work.

If you want easy/safe, buy a Carbonda frame and Elitewheels wheel set.  Then plan on mainstream Taiwanese and Japanese brands (Rockshox/Fox/Suntour/Xfusion and Shimano/SRAM/Microshift) for most of the rest. 

Edit - Heard from Wing:

120MM travel :
Pre-order accepted, expected to be available in spring 2023,
deposit: $100（No refund on cancellations）
 
FM 936 -Normal version ( 120  mm travel  ) : US $ 695
FM 936  Super Light version ( 120  mm travel  ) : US $ 810

You might want to change your title from "Downcountry" to "Hardtail", or at least include both.  To me, "downcountry" means a full suspension light trail bike.