Thanks all. The order has shipped after a considerable delay. I'll post a small review once it's here!
Update on Shimano Deore 12s mini groupset that I ordered. It reached to me today.
From what I can see, the shifter and RD look genuine Shimano with pretty high quality finish on both. No smudges, grease marks or dust at all. But absolutely no paperwork either - no manual, stickers nothing. Just thick plastic bag for each. The cable came attached to shifter and it's the Teflon coated type which makes me happy.
The chain is KMC X12 which also looks OG but I don't have reference chain from say REI or LBS. For now, it passes as genuine.
Finally the cassette which is riveted together almost 90% of cogs except the last two. Has an interesting red colored spider inside holding all together. Installed without any fuss but shift performance is strictly okay. Can't hold a candle to my well used Ultegra cassette on other build. Not even close to 105 cassette either.
I think that the machining is not precise and hoping that any sharp edges will be worn off with use and performance might improve? In any case it's not the best but it's not the worst either. It's on my now-converted-to-flatbar bike which will see occasional use.
Attaching pictures, just in case.