I'm aware of it, and I'm not aware of anyone using it for proprietary software in the kinds of projects where Ada would come up in discussion. FSF GNAT + Alire are fine as a hobbyist toy and for open source, but they're not in contention for [workjob]. FSF GNAT isn't just unsupported, but also very thinly documented. And that's if you're only targeting Linux or Windows on x86, and not embedded devices with a cross-compiler you need to build yourself.

The basic Windows / Linux versions of the cheapest commercial Ada package only recently dropped to high 4-figures / seat. The equivalent cross-compilers are still $$,$$$.