And in that also the cpu cores, all i/o (pcie, usb, …), special sound units, ms own mojo, …
My math is different than yours, assuming a fixed 120mm2 for the uncore leaving the rest just for the units, would leave:
Navi21* – 505mm^2 = 100CUs
Navi22 – 340mm^2 = 64CUs
Navi23 – 240mm^2 = 40CUs
Used the XSX has reference with 200mm2 for units.
*Two different memory types supported on this one.