Yes, the 2/3/4 are all 64 bit. The Zero/Zero W are the same old 32 bit ARM11 hardware as the original Pi. Raspbian is still armhf but there are several aarch64

Yes, the 2/3/4 are all 64 bit. The Zero/Zero W are the same old 32 bit ARM11 hardware as the original Pi. Raspbian is still armhf but there are several aarch64 distros available (Arch, Fedora, Debian) for the recent Pi models.