Since the OP asked if anyone would buy a df in 2021, I’ll just chime in as someone who has done.
Recently bought a s/h silver Df, (technically at the end of 2020 but) it arrived begining of 2021. I couldn’t resist since it was on sale nearly mint with a silver ring 50 1.8 for about US$1k. 4500 shutter actuations dated 2017. Note that this is about the same price as a second hand Z6 which can also be bought for about $1k
I bought it because I just wanted a fresh perspective and something to remind me of my Nikon SP/F3/F4 that I used to rock back in the late 90s. Knowing full well I have neither the time nor patience for film.
I am aware that a Z series camera would have also been a fresh perspective, but as someone who used the D4 professionally for half a decade, I already knew what the D4 sensor was capable of, so I consider it a steal. Its “bad rep” is working its price downwards favorably for the s/h market, but making a df2 all but impossible.
For me, the Df represents a perfect storm of balance and necessary compromise.
Here are the things that stand out after 4 months’ ownership.
Size and weight is just right for older AFD and MF lenses
resolution strikes the best balance for IQ/file processing size and speed.
D4 sensor was an inspired choice of sensor with its balance between sensitivity and resolution.
These two factors make it very forgiving of pre-millenial glass from an IQ standpoint.
Handling is a brilliant balance between D and F series.
Design is a decent balance between retro and modern:
It doesn’t impose like a modern black DSLR and subjects seem less self conscious.
With a dk-17m magnifier, the viewfinder image is a decent balance between size and magnification:
big enough to work with MF glass but not too big to still be compact or heavy in the hand.
The small sensor resolution means live view update speed is faster than the D800 series and great for nailing f/1.2 at close range.
In fact, IMHO, it's so well balanced that Thanos would probably approve.
Whether you consider them compromises or great balance, is up to you, but for me, not a shred of buyer’s remorse.
Has be come my pleasure photo-cruise camera of choice.
Anyway, OP asked if I would buy one and I say, if you have the money and are looking for something other than the latest and greatest or already own the latest and greatest, then go for it.