Yea the pricing of those QLED models are a little silly . Q6FN is pretty much just like NU8000 except it is a Quantum Dots display , so it is slightly more colorful than NU8000 but I find its pricing a little absurd because it doesn't offer much over the NU8000.
The NU8000 is a bright TV but it isn't that bright compare with the likes of Z9D , Q9FN , Q7FN.

If your wife doesn't like the TV being too bright , you can always turn down the luminance settings .

When you have a bright TV  you have the luxury to adjust the brightness to suit your needs.
While playing HDR content , some of those effects can look really eyepopping on brighter TVs .

Note : although brightness is not the only factor to determine HDR performance
NU8000 is the successor of MU7000 , MU8000 is a step up over MU7000 . The MU8000 uses full glossy screen coating , which can provide better anti reflection in a bright room. Beside that , MU8000 and MU7000 are pretty identical .  Yea I know all these model numbers are very confusing .
Credit from rtings

VESA isn't a brand, it is a grouping of 300 ++ companies coming together setting a standard across the brands.

The VESA mounting standards is used by most TV/Panels for the measurement of mounting interface.

NU8000 has a VESA 200X200 If I remember correctly , but the one I linked you is flexible enough to hold a 65 inches NU8000 , since it weights around 33kg .

How to check Samsung nu8000 total run time ya?