I would like to install an older Android version on a Pixel 3a. I saw the system images provided by Google, but they only offer Android9.0-10.0 (see here). I already unlocked the bootloader, so I think I'm ready to start the flashing. For testing purposes I want to install Android5.0 and Android7.0.
Unfortunately, a virtual android device is not feasible for my use-case, this is why I have to run the version on the real device.
Now, I know that I can just go ahead and build these versions myself (as described here), but I'm not sure if this will work. Is the Pixel 3a compatible with Android versions that were never meant to run on it? And is there a faster way to just test boot different versions, by downloading the system image (just like with this list). I saw forum entries, that stated, downloading the android source takes up to 24h...
Thanks for any hints! And tips for the general build procedure
