CXL is a standard for compute and I/O extension over PCIe signaling which has been around for a few years, with a couple of available RAM boards (from SMART and others).

I think the main bridge chipsets come from Microchip (this one) and Montage.

This Gigabyte product is interesting since it’s a little lower end than most AXL solutions - so far AXL memory expansion has mostly appeared in esoteric racked designs like the particularly wild https://www.servethehome.com/cxl-paradigm-shift-asus-rs520qa... .

CXL seems so much cleaner than the old AMD way of plumbing an FPGA through the second CPU socket.