Something that some security conscious folks care about.
By the way Linux does it, but then again Oracle has its own distro.
https://www.oracle.com/servers/sparc
Linux while not being UNIX, does support it as Oracle upstreamed SPARC ADI support during the brief time they had Oracle Linux support for SPARC.
https://docs.kernel.org/arch/sparc/adi.html
Now why someone would use unsupported OpenBSD on SPARC for the kinds of clients that pay for this stuff, beats me.
Assuming it does even support SPARC ADI.
Why would someone use unsupported OpenBSD on SPARC for the clients that pay for it? Probably the same reason so many servers run on Rocky or Alma instead of RHEL, money. Perhaps they bought the hardware without the support contract for Solaris, or they don't want to keep paying for it
Probably impractical for most server workloads (so not an alternative to Solaris on SPARC) but worth mentioning.
I'm sure Oracle milks commercial Solaris efficiently, but I imagine it's hard to find new customers for it.
And who was it who benefited from this stuff? A lot of the benefit went to "megacorps" who took the savings and banked the higher profits.
So I don't think open source, which for many years was unashamedly about just cloning designs that were funding other people's salaries, can really cry too much about LLMs. And I say that as someone who has written a lot of open source software, including working on Wine.