Mac Pro only comes with Xeons, so these are Hackintoshes.
I don't think that you can put an i9 in a Xeon socket and I think that Xeon systems typically use ECC RAM.
Xeon is a wide class of processors. Up until Gen 12 Intel was regularly doing a Xeon version of the mainstream processor. Just a matter of turning features on/off on the die. For example
" ...Code Name Products formerly Rocket Lake ...
...
- Total Cores 8
- Total Threads 16
- Max Turbo Frequency 5.20 GHz
Sockets Supported FCLGA1200 ... "
Intel® Core™ i9-11900 Processor (16M Cache, up to 5.20 GHz) quick reference guide including specifications, features, pricing, compatibility, design documentation, ordering codes, spec codes and more.
ark.intel.com
" ...
Code Name Products formerly Rocket Lake
...
- Total Cores 8
- Total Threads 16
- Max Turbo Frequency 5.10 GHz
....
Sockets Supported FCLGA1200 ... "
Intel® Xeon® E-2378G Processor (16M Cache, 2.80 GHz) quick reference guide including specifications, features, pricing, compatibility, design documentation, ordering codes, spec codes and more.
ark.intel.com
Same with the Xeon 1xxx series
Intel® Xeon® W-1370P Processor (16M Cache, up to 5.20 GHz) quick reference guide including specifications, features, pricing, compatibility, design documentation, ordering codes, spec codes and more.
ark.intel.com
It isn't about Xeon or not. It is about the designated workstation class CPU package (e.g., Xeon E5 , W-2xxx , W-3xxx ). If stuck with Intel likely not backsliding on PCI-e lane count from the CPU package . (e.g., Gen 13 i9 is 20 lanes. Where the MP 2019 is carrying 64).
Pretty good chance Apple silicon will backslide on lane provisioning, but if were going to stick with Intel and wanted to minimize main logic board changes from the MP 2019 , it would be something else with a better lane count match.
Intel is struggling to just get Gen 12/13 out the door with the subset they are committed to so the W-1xxxx is dragging.