I'm sure I read in one of the recent Ryzen reviews that AMD used the 12nm process to drive performance instead of density, so I guess you have a choice. Maybe GV100 was originally designed for 16nm, then perhaps Nvidia went the same route.
The traditional word for that in CPU design is "Implementation", possibly "Organisation", but they don't sound very sexy in marketing junk.
Perhaps I'm just old. If I look in my second edition of Hennessy and Patterson (the book that current CPU designers would have learnt their craft from), the Index at the back doesn't contain the word microarchitecture and I don't remember reading it in there, so if all the implementations of the day could be described in detail without using the word it can't be that critical. I wonder if it is in the new edition, which I am tempted to get if only to read a good analysis of RISC-V. Mind you, H&P use "architecture" to cover organisation, some would be find that irritating
Anyway, I'm not going to fight the whole Internet over their current insistence on using the phrase