The NetBSD port for DEC’s RISC-based “Alpha” architecture. Currently still supported.

https://www.openbsd.org/alpha.html

The NetBSD port for the arm64 architecture. Runs on a bunch of boards and things.

https://www.openbsd.org/arm64.html

The NetBSD port for the armv7 architecture. Runs on a bunch of boards and things.

https://www.openbsd.org/armv7.html

The OpenBSD port to the i386 architecture.

https://www.openbsd.org/i386.html

The OpenBSD port to the octeon architecture, which has various network-based hardware and similar MIPS-based devices.

https://www.openbsd.org/octeon.html