José Andorno at 9to5Mac has this article on an interview Bloomberg’s Mark Gurman gave.
It is really interesting that it says there was a M1 MacPro ready but they decided to wait for the M2, which means they won’t make the 2 year promise on the move to Apple Silicon.
Honestly it is likely because the M1 could only do dual, and the performance would not have been hugely more than the Mac Studio if there was not a quad option. So likely the M2 can do Quad.