There are likely to be things that don't work yet on aarch64, I would
leave the kernel option on for now.
MKCOMPAT=yes for aarch64 builds aarch64, earm and oarm though, I don't
think we need all of them.
It does work already. That is the option.
Currently COMPAT_NETBSD32 supports EABI only, and I will not be
supporting OABI in the future. There is also a technical reason
that sys/compat/netbsd32 can only have one instance.
#If someone is going to do it will support :)
I think there is no need to build at least oarm with MKCOMPAT=yes.