After a year of beta testing, a stable version of the 64-bit version of Raspberry Pi OS is finally available. This long-awaited operating system increases software compatibility for closed-sourced applications, which are often exclusive to ARM64. Additionally, 64-bit Pi OS should improve benchmark performance (not necessarily real-world performance) thanks to its improved instruction set.
Most Raspberry Pi SoCs released since 2016 have 64-bit processors, which allow them to run 64-bit operating systems like Windows or the new Pi OS. For reference, the 64-bit Pi OS works on the Pi 3, Pi 4, Pi Zero 2, and all variants on these machines (such as the Pi 400).
Unfortunately, the Pi Foundation is still working on the “desktop with recommended apps” version of the 64-bit Pi OS. If you want to upgrade today, you’ll have to install the “Lite” version of Pi OS and manually install important applications. (I should also note that the new Pi OS is based on Debian 11 “Bullseye,” rather than the legacy Debian 10 “Buster.”)
And just to be clear, the Raspberry Pi Foundation says that it will continue to support 32-bit Raspberry Pi OS, as older hardware like the Pi 2 lacks the necessary hardware for 64-bit applications.
You can install the 64-bit Pi OS from the Pi Foundation’s software page. (If you plan to use platforms like Netflix or Disney+ with the new Pi OS, you may want to follow the Chromium instructions at the bottom of the Pi Foundation’s announcement page.)
Source: Raspberry Pi Foundation