Of course, I may be macOS-biased here :-)
Remarks at [1],
"We see a majority in favor or recommending GNAT FSF.
"The result is less clear for the removal of GNAT community. The
comments along the answers show that people against this are worried
about the ease of use. So we are going to work on that aspect."
"We don't expect anyone to build GCC/GNAT themselves, and that is why
part of our plan is to help maintainers of OS distribution make good
GNAT package."
"AdaCore will continue to provide the SPARK toolset on Linux and
Windows. There is no runtime coming with the toolset, so no possible
license confusion, it's only an analysis tool!"
[[Can we run Linux apps in Docker on a Mac? looks possible, and might
I think be an OK solution for gnatprove given the above. M1 macs??]]
and [2],
"Most likely this version of the compiler will be the last in the
GNAT Community Edition release chain. In the future, the compiler
collected from open source GCC texts can be installed using a batch
manager Alire."
[1]
https://www.reddit.com/r/ada/comments/j6oz6i/results_of_the_survey_on_the_future_of_gnat/
[2]
https://www.altusintel.com/public-yy39qc/