from what I understand, it's not practical to build natively on ARM.
People use poudriere combined with qemu to do that, and I believe somebody is building packages for public use.
to directly answer you question:
It would be technically possible to support arm (in fact I created the gnatdroid cross compiler which is a cross-compiler FreeBSD->Android (ARM and X86)) but there's been no demand and as I said, building packages natively on arm is impractical. gcc alone takes forever.