IMac Pro

The iMac Pro is a discontinued all-in-one personal computer and workstation designed, manufactured, and sold by Apple Inc. It was released on December 14, 2017. While it was sold, it was one of four desktop computers in the Macintosh lineup, sitting above the consumer range Mac Mini and iMac, and serving as an all-in-one alternative to the Mac Pro. 
Overview.
The iMac Pro was introduced at WWDC on June 5, 2017 and was released in December 2017. Apple billed it as "the most powerful Mac ever made". Its starting price is $4999. It includes an 8-, 10-, 14-, or 18-core Intel Xeon processor, 5K display, AMD Vega graphics, ECC memory, and 10 Gigabit Ethernet. It includes a custom Apple T2 chip to store encrypted keys, and a custom version of macOS that allows the user to lock down the booting process. On March 19, 2019, options for 256 GB of memory and a Vega 64X GPU were added. On August 4, 2020, Apple discontinued the 8-core model and made the 10-core model, previously an upgrade option, the base model. 
On March 5, 2021, Apple discontinued the iMac Pro and said it would continue selling it while supplies last. It was delisted from Apple's website and online store on March 19, 2021.
Design.
The iMac Pro's chassis is carried over from the 27-inch iMac introduced in 2012 but is only available in a darker "space gray" finish. Unlike the white accessories that come with the iMac, the iMac Pro comes with a black Magic Keyboard with a numeric keypad, and a black Magic Mouse or Magic Trackpad.
Repairability.
The processor, memory, and storage are not soldered and can be removed. Unlike the 27-inch iMac, the iMac Pro does not have a memory access port, though memory can be upgraded by Apple Stores and authorized service providers. User replacement of memory is possible as it is not soldered, though it requires disassembling the display. 
The iMac Pro is the first model to be equipped with Apple's T2 co-processor. This results in a non-user-replaceable solid state drive as the SSD modules are paired cryptographically with the T2 chip, even though the SSD is not soldered on the motherboard like many MacBook models. It theoretically can be replaced as it is possible to remove it, although doing so requires an extensive disassembly, and only some drives are compatible. 
The iMac Pro's stand is user-replaceable with a VESA mount kit sold by Apple. The mount uses zinc screws that may be prone to breaking. Although the VESA adapter is branded as an Apple product, it is actually a licensed OEM product and Apple does not provide support for it.
Reception.
The iMac Pro was generally well-received.