But Linux is not better. Android at least has permissions for apps and allows you to deny some of it; on a typical desktop Linux distribution or on Windows ever

But Linux is not better. Android at least has permissions for apps and allows you to deny some of it; on a typical desktop Linux distribution or on Windows every app has full access to all of your data: a calculator can read your browser history. If you install the Slack app from Deb package on Linux, it will add its repository into APT sources list which means that Slack Inc. can now "patch" any program on your system, for example, sshd or Firefox. Also, it will add a daily cron task that checks that added configuration is not commented out (they explain that it is necessary for the case of upgrading a distribution). Such behaviour is simply impossible on Android. So I think it is the opposite: mobile OS provide better security than desktop OS.