For developers, building a custom GSI from AOSP source is possible but resource-heavy:

Developers use these images to test apps on the latest Android versions without needing the official manufacturer update for their specific device.

system-arm64-ab.img.xz is a compressed Generic System Image (GSI)

Verify connection:

The .xz extension denotes that the file is compressed using the XZ compression algorithm, which helps reduce the file size and make it easier to transfer.