I usually build systems based on Matx or Itx boards.  Saw the Nuc 9 Extreme and decided to go for it.  Glad I did.  Purchased from Hot Tech Geek and shipped by Amazon.  Received as advertised, brand new, sealed and undamaged..  Mine came with a US plug taped to the top.  I do have a warning- When you do the bios Update, it will reboot and turn off.  Mine was dead and would not respond.  Not good for being 15 minutes old and almost made a grown man cry.  I unplugged it for a couple of minutes and it turned on no problem.  Only happened after bios update.  I added 2 x 16gb Crucial DDR4 3200 -CT16G4SFRA32A and a 4Tb WD 850X- WDS400T2X0E.  The first boot took a minute with a black screen.  The nice thing is that you don't have to remove the CPU card to install the ram or two top Nvme's.  Intel says you can put a 2.5inch Sata SSD, but good luck with that- I don't know where you would mount it.  I am using it as a desktop and for network system mgmt.  I do not have a dedicated video card installed as I don't play games.  I installed a dual 10gbe network card and it works fine.  Software-  I have tried Windows 10 and 11 without issues.  I also tried a version of Linux which worked with tweaks of the kexts and using open core ( alcid=14 will make your sound work, usb mapping - I am still working on with a usb2 speed limit with all ports working, BT yes, Wifi no).  Works wonderful in Plex.  Transcoded 5 streams without any issues or stuttering and while using the machine normally.  Temps are good. I changed my fan curve and lowered the power top limit to 90watts max boost.  Fans are at 20 perfect with a 35 C idle temp.  Any PCI-e expansion cards are limited to 8 inches MAX.  I tried a EVGA 3060 XC 12gb and it fit.  Founders Nvidia 3000 series cards do not, no matter how much I wish it could.  IF you want a 13th Gen Intel with a larger video card, this is not for you.  If you want a compact machine that will handle just about everything, this is a good choice.