Indeed, Android 14 may prevent users from sideloading really ancient applications. Since some malware is developed for earlier versions to evade a permissions system introduced in 2015, Google will mandate that applications target at least Android 6.0 (Marshmallow). This will not prohibit you from using programs already installed when you update 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 alternatives.
