commercially, but there’s also https://capyloon.org/

offering a GSI too, so if you have a modern Android lying around you can install it

there’s a magisk module for microG Androids (https://github.com/sn-00-x/aa4mg) that brings in some proprietary AA stubs that work in that environment. It pulls in the necessary gplay dependencies (assistant aka velvet, tts engine(?) and Maps). You could use https://github.com/casualsnek/waydroid_script and load this module in magisk.

Then there’s a thread where users assemble a patchset for ROM / Android GSI builders to use AA as a user app, making it more accessible than it being a priv-app - https://github.com/microg/GmsCore/issues/897