While the primary issue is likely developer time and hardware availability to test on, there are other OSs like OpenBSD which supports much newer SPARC64 hardware: https://www.openbsd.org/sparc64.html
OpenBSD is the only OS ever to run on my Tadpole laptops without any modification necessary. Even Solaris 8 and 10 needed special software to run on them. OpenBSD works right out of the box.
SPARC was where Theo cut his teeth in the netbsd years, anecdotal but I think it’s his favourite pet so you’d imagine it’ll be well supported on his os
>The other architectures that OpenBSD supports have benefited because some kinds of bugs are exposed more often by the 64-bit big endian nature of UltraSPARC.
I can’t really tell if they’re just dropping older SPARC systems or the architecture altogther.
OpenBSD will eventually face the same issues with older systems, and I believe they already dropped platforms because hardware couldn’t be replaced.
For newer SPARC system you could “just” buy one. Oracle doesn’t need to donate them, it would be nice if they did, but the community around Illumos, Debian and OpenBSD could raise money to buy theses systems.