Indeed, Android 14 can prevent users from sideloading really ancient applications. Because some malware is developed for older versions to evade a permissions system introduced in 2015, Google will mandate that apps target at least Android 6.0 (Marshmallow). This will not prohibit you from using programmes that are already installed when you upgrade the System, and you may force installs using command line instructions. If you have an old app that you don’t want to give up, you may have to explore for alternatives.
