I am building AOSP 12 for my Pixel 3a sargo. It worked but I wanted to install Gapps on it. When I tried to flash any Gapps zip in TWRP, it said that my system partition was read-only or full, so I tried remounting it with the read and write permissions. But it showed the same thing. After that, I saw that my system partition was full. So I was wondering, how I can include Gapps while building AOSP? But since OpenGapps is not available for Android 12 (I tried but the build failed), I don't know how to include Gapps in my build.
Can someone help me, please?