I'm running PixelOS.Hi spirit, I tried to install the following Leica Cam: https://drive.google.com/file/d/13u4TiYqPSAYueBUitRauaa_kgFE7oCYj/view
but it didn't install. It says the package is invalid.
The zip-file also didn't install using recovery. https://drive.google.com/file/d/19qEGNjcigX_Ku85XYtXjVQJd4Br8RPCu/view
In order to try helping You, I made the same test as You with the same result :
- APK : the package seems not to be valid ;
- ZIP : process finished with Error 1.