As Arty Johnson used to say…

Very interesting, but stupid…
My honest opinion of Nikon cameras DSLR, DX, FX, and mirrorless…
I have 3 Nikons – D5600, D810, D850. First, the 2 full frames (D810 and D850) are behemoths and with the larger lenses I need a tripod that is capable of handling around 24lbs. Second. the D5600 which has WiFi built in is smaller, lighter, and is quick and nimble -but the D850 which also has WiFi support, weighs a ton but is quick. The D5600 is also supposed to have GPS support built in. But nothing in the Nikon world is more full of crap than “supportive GPS”. Its highly complex, slow as hell, and requires steps that would frustrate the most patient person. The D850 pulls location data easily/seamlessly from the iPhone while the others do not. However, you have to move the pictures to your iPhone or Apple Cloud. Third, from a shot perspective, you can fit more in in the same shot with a FX vs DX. I used to joke with a friend to take 2 big steps back and get the same shot and save money. Fourth, only the D850 does movies easily, the other 2 are a PITA.
I like the professional looking pictures from the D810 and the D850 vs the D5600 – better bokeh, better lenses, higher megapixel counts, a longer shelf life (equates to more pictures over the life of the camera), the D850 is also a much faster camera than the D5600 or the D810 – from both a chip and consequently a focus and picture processing perspective.
I’ll take the D850 – anytime. I don’t know if I would take the D810 over the D5600 knowing what I know now – I think I would recommend living with the D5600. Mirrorless vs the D850? I don’t think it’s worth it – save your money.
-Rat