I missed this news, via Jeff Geerling:

Yesterday Raspberry Pi announced the 64-bit version is finally official. It’s no longer hidden away in a crusty forum link, it’s linked straight from their public downloads page and the Raspberry Pi Imager.

The download page still displays the default 32-bit version first, but having 64-bit as an official option is a big step.

Going to 64-bit isn’t an automatic win in and of itself; the original few generations of hardware don’t support it, and you do lose a bit of memory. But as more software targets 64-bit specifically, I’m sure we’ll start to see it listed as a requirement.

64-bit FreeBSD has also been available for a while. Those interested can check out this page published by the FreeBSD Foundation.