Hmm,
I am running Qemu 10.1.2 from Homebrew on an M1 CPU Mac. Here is my command line for my build VM:
qemu-system-sparc -M SS-20 -m 1536 -smp 2 -drive file=sparc-10-1.qcow2,bus=0,unit=0,media=disk -drive file=NetBSD-10.1-sparc.iso,bus=0,unit=2,media=cdrom,readonly=on -nic user,hostfwd=tcp::8888-:22