The most prominent free Android 13 distribution for the Galaxy S2 is LineageOS 20 , an open-source operating system based on Android 13. Unofficial builds are maintained by independent developers on forums such as XDA Developers. These builds are completely free of charge, distributed under open-source licenses, and require the user to unlock the bootloader, install a custom recovery (e.g., TWRP), and manually flash the ROM and a compatible lightweight GApps (Google Apps) package or forgo Google services entirely.

There is for the S2. However, some developers have backported Go optimizations (lighter launcher, limited background processes) into their kernels. You can emulate this by installing "Go" versions of Google Apps (GApps).

The toolkit used to wipe the old OS.

While you can technically get Android 13 for free on the Samsung Galaxy S2, it is a complex DIY project intended for enthusiasts. It’s a testament to the S2's build quality and the power of the developer community that a phone from 2011 can even boot an OS from 2022.

Google Apps (GApps) are free but drastically degrade performance. Use MindTheGApps-13.0.0-arm-20231025.zip if needed.