@dehjomz,
Apple manufactures and sells a range of Radeon Pro Vega II MPX cards for the 2019 Mac Pro ...
All those cards use the same GPU die that is used on the AMD Radeon VII.
Apple has always been traditionally very slow when it comes to supporting a new GPU architecture, for instance when Apple added support for Vega II (as used in Radeon VII cards) it took well over 8+ months before the drivers could be considered usable, the same was true for 5000 series Navi.
It is expected that Apple will refresh the 2019 Mac Pro later this year, as part of that refresh I would expect Apple to announce new MPX modules for the 2019 Mac Pro based on AMD 6000 series GPU's at which point we can expect to start to see fully working drivers for 6000 series GPU's being introduced into MacOS.
Personally i would not expect that to happen to maybe Big Sur 11.5 ... even then there will most likely be teething issues which traditionally have not been fully resolved until the next release of MacOS.
This is the way its been for many years and is just the way the Apple rolls ....
Cheers
Jay