"The OpenBSD/sgi port was discontinued after the 6.5 release."

That said, it was a very mature port and ran on many models, in 64-bit mode.

The code remains in -current for now.. the last release, 6.5 is a complete modern (was released in 2019) Unix operating system, which is more than can be said for running IRIX or Linux on these machines. I'm not even _aware_ of any binary distros of Linux for these. And good luck building your own kernel and userland.